Upgrade vendored distro to use new typing and API

The most recent version of distro, 1.6.0, include type information. This
allows pip to remove some workarounds. See upstream commit:
https://github.com/python-distro/distro/commit/20cb68d6b00179135f1461d51972fb3395e75363

The new version also deprecated the top level function
distro.linux_distribution(). Switch to the new preferred API. See
upstream commit:
https://github.com/python-distro/distro/commit/f947776f5a9f018325f0daa446b92d62f1811a91

6 files changed, 335 insertions, 189 deletions

diff --git a/news/c8285e11-5b65-498c-9eaa-85ca096243f9.vendor.rst b/news/c8285e11-5b65-498c-9eaa-85ca096243f9.vendor.rst
new file mode 100644
index 000000000..759696ce2
--- /dev/null
+++ b/news/c8285e11-5b65-498c-9eaa-85ca096243f9.vendor.rst
@@ -0,0 +1 @@
+Upgrade distro to 1.6.0.
diff --git a/pyproject.toml b/pyproject.toml
index 9f6dbe12a..f54c016ac 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -51,6 +51,7 @@ drop = [
 [tool.vendoring.typing-stubs]
 six = ["six.__init__", "six.moves.__init__", "six.moves.configparser"]
 appdirs = []
+distro = []
 
 [tool.vendoring.license.directories]
 setuptools = "pkg_resources"
diff --git a/src/pip/_internal/network/session.py b/src/pip/_internal/network/session.py
index faaae4059..fe1cf717e 100644
--- a/src/pip/_internal/network/session.py
+++ b/src/pip/_internal/network/session.py
@@ -2,16 +2,6 @@
 network request configuration and behavior.
 """
 
-# When mypy runs on Windows the call to distro.linux_distribution() is skipped
-# resulting in the failure:
-#
-#     error: unused 'type: ignore' comment
-#
-# If the upstream module adds typing, this comment should be removed. See
-# https://github.com/nir0s/distro/pull/269
-#
-# mypy: warn-unused-ignores=False
-
 import email.utils
 import ipaddress
 import json
@@ -128,9 +118,8 @@ def user_agent() -> str:
     if sys.platform.startswith("linux"):
         from pip._vendor import distro
 
-        # https://github.com/nir0s/distro/pull/269
-        linux_distribution = distro.linux_distribution()  # type: ignore
-        distro_infos = dict(
+        linux_distribution = distro.name(), distro.version(), distro.codename()
+        distro_infos: Dict[str, Any] = dict(
             filter(
                 lambda x: x[1],
                 zip(["name", "version", "id"], linux_distribution),
diff --git a/src/pip/_vendor/distro.py b/src/pip/_vendor/distro.py
index 0611b62a3..789274134 100644
--- a/src/pip/_vendor/distro.py
+++ b/src/pip/_vendor/distro.py
@@ -20,26 +20,61 @@ machine-readable distro ID, or version information.
 It is the recommended replacement for Python's original
 :py:func:`platform.linux_distribution` function, but it provides much more
 functionality. An alternative implementation became necessary because Python
-3.5 deprecated this function, and Python 3.8 will remove it altogether.
-Its predecessor function :py:func:`platform.dist` was already
-deprecated since Python 2.6 and will also be removed in Python 3.8.
-Still, there are many cases in which access to OS distribution information
-is needed. See `Python issue 1322 <https://bugs.python.org/issue1322>`_ for
-more information.
+3.5 deprecated this function, and Python 3.8 removed it altogether. Its
+predecessor function :py:func:`platform.dist` was already deprecated since
+Python 2.6 and removed in Python 3.8. Still, there are many cases in which
+access to OS distribution information is needed. See `Python issue 1322
+<https://bugs.python.org/issue1322>`_ for more information.
 """
 
+import argparse
+import json
+import logging
 import os
 import re
-import sys
-import json
 import shlex
-import logging
-import argparse
 import subprocess
+import sys
+import warnings
+
+__version__ = "1.6.0"
+
+# Use `if False` to avoid an ImportError on Python 2. After dropping Python 2
+# support, can use typing.TYPE_CHECKING instead. See:
+# https://docs.python.org/3/library/typing.html#typing.TYPE_CHECKING
+if False:  # pragma: nocover
+    from typing import (
+        Any,
+        Callable,
+        Dict,
+        Iterable,
+        Optional,
+        Sequence,
+        TextIO,
+        Tuple,
+        Type,
+        TypedDict,
+        Union,
+    )
+
+    VersionDict = TypedDict(
+        "VersionDict", {"major": str, "minor": str, "build_number": str}
+    )
+    InfoDict = TypedDict(
+        "InfoDict",
+        {
+            "id": str,
+            "version": str,
+            "version_parts": VersionDict,
+            "like": str,
+            "codename": str,
+        },
+    )
 
 
-_UNIXCONFDIR = os.environ.get('UNIXCONFDIR', '/etc')
-_OS_RELEASE_BASENAME = 'os-release'
+_UNIXCONFDIR = os.environ.get("UNIXCONFDIR", "/etc")
+_UNIXUSRLIBDIR = os.environ.get("UNIXUSRLIBDIR", "/usr/lib")
+_OS_RELEASE_BASENAME = "os-release"
 
 #: Translation table for normalizing the "ID" attribute defined in os-release
 #: files, for use by the :func:`distro.id` method.
@@ -49,7 +84,7 @@ _OS_RELEASE_BASENAME = 'os-release'
 #:
 #: * Value: Normalized value.
 NORMALIZED_OS_ID = {
-    'ol': 'oracle',  # Oracle Linux
+    "ol": "oracle",  # Oracle Linux
 }
 
 #: Translation table for normalizing the "Distributor ID" attribute returned by
@@ -60,11 +95,11 @@ NORMALIZED_OS_ID = {
 #:
 #: * Value: Normalized value.
 NORMALIZED_LSB_ID = {
-    'enterpriseenterpriseas': 'oracle',  # Oracle Enterprise Linux 4
-    'enterpriseenterpriseserver': 'oracle',  # Oracle Linux 5
-    'redhatenterpriseworkstation': 'rhel',  # RHEL 6, 7 Workstation
-    'redhatenterpriseserver': 'rhel',  # RHEL 6, 7 Server
-    'redhatenterprisecomputenode': 'rhel',  # RHEL 6 ComputeNode
+    "enterpriseenterpriseas": "oracle",  # Oracle Enterprise Linux 4
+    "enterpriseenterpriseserver": "oracle",  # Oracle Linux 5
+    "redhatenterpriseworkstation": "rhel",  # RHEL 6, 7 Workstation
+    "redhatenterpriseserver": "rhel",  # RHEL 6, 7 Server
+    "redhatenterprisecomputenode": "rhel",  # RHEL 6 ComputeNode
 }
 
 #: Translation table for normalizing the distro ID derived from the file name
@@ -75,30 +110,39 @@ NORMALIZED_LSB_ID = {
 #:
 #: * Value: Normalized value.
 NORMALIZED_DISTRO_ID = {
-    'redhat': 'rhel',  # RHEL 6.x, 7.x
+    "redhat": "rhel",  # RHEL 6.x, 7.x
 }
 
 # Pattern for content of distro release file (reversed)
 _DISTRO_RELEASE_CONTENT_REVERSED_PATTERN = re.compile(
-    r'(?:[^)]*\)(.*)\()? *(?:STL )?([\d.+\-a-z]*\d) *(?:esaeler *)?(.+)')
+    r"(?:[^)]*\)(.*)\()? *(?:STL )?([\d.+\-a-z]*\d) *(?:esaeler *)?(.+)"
+)
 
 # Pattern for base file name of distro release file
-_DISTRO_RELEASE_BASENAME_PATTERN = re.compile(
-    r'(\w+)[-_](release|version)$')
+_DISTRO_RELEASE_BASENAME_PATTERN = re.compile(r"(\w+)[-_](release|version)$")
 
 # Base file names to be ignored when searching for distro release file
 _DISTRO_RELEASE_IGNORE_BASENAMES = (
-    'debian_version',
-    'lsb-release',
-    'oem-release',
+    "debian_version",
+    "lsb-release",
+    "oem-release",
     _OS_RELEASE_BASENAME,
-    'system-release',
-    'plesk-release',
+    "system-release",
+    "plesk-release",
+    "iredmail-release",
 )
 
 
 def linux_distribution(full_distribution_name=True):
+    # type: (bool) -> Tuple[str, str, str]
     """
+    .. deprecated:: 1.6.0
+
+        :func:`distro.linux_distribution()` is deprecated. It should only be
+        used as a compatibility shim with Python's
+        :py:func:`platform.linux_distribution()`. Please use :func:`distro.id`,
+        :func:`distro.version` and :func:`distro.name` instead.
+
     Return information about the current OS distribution as a tuple
     ``(id_name, version, codename)`` with items as follows:
 
@@ -122,10 +166,18 @@ def linux_distribution(full_distribution_name=True):
     method normalizes the distro ID string to a reliable machine-readable value
     for a number of popular OS distributions.
     """
+    warnings.warn(
+        "distro.linux_distribution() is deprecated. It should only be used as a "
+        "compatibility shim with Python's platform.linux_distribution(). Please use "
+        "distro.id(), distro.version() and distro.name() instead.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
     return _distro.linux_distribution(full_distribution_name)
 
 
 def id():
+    # type: () -> str
     """
     Return the distro ID of the current distribution, as a
     machine-readable string.
@@ -205,6 +257,7 @@ def id():
 
 
 def name(pretty=False):
+    # type: (bool) -> str
     """
     Return the name of the current OS distribution, as a human-readable
     string.
@@ -244,6 +297,7 @@ def name(pretty=False):
 
 
 def version(pretty=False, best=False):
+    # type: (bool, bool) -> str
     """
     Return the version of the current OS distribution, as a human-readable
     string.
@@ -288,6 +342,7 @@ def version(pretty=False, best=False):
 
 
 def version_parts(best=False):
+    # type: (bool) -> Tuple[str, str, str]
     """
     Return the version of the current OS distribution as a tuple
     ``(major, minor, build_number)`` with items as follows:
@@ -305,6 +360,7 @@ def version_parts(best=False):
 
 
 def major_version(best=False):
+    # type: (bool) -> str
     """
     Return the major version of the current OS distribution, as a string,
     if provided.
@@ -318,6 +374,7 @@ def major_version(best=False):
 
 
 def minor_version(best=False):
+    # type: (bool) -> str
     """
     Return the minor version of the current OS distribution, as a string,
     if provided.
@@ -331,6 +388,7 @@ def minor_version(best=False):
 
 
 def build_number(best=False):
+    # type: (bool) -> str
     """
     Return the build number of the current OS distribution, as a string,
     if provided.
@@ -344,6 +402,7 @@ def build_number(best=False):
 
 
 def like():
+    # type: () -> str
     """
     Return a space-separated list of distro IDs of distributions that are
     closely related to the current OS distribution in regards to packaging
@@ -361,6 +420,7 @@ def like():
 
 
 def codename():
+    # type: () -> str
     """
     Return the codename for the release of the current OS distribution,
     as a string.
@@ -385,6 +445,7 @@ def codename():
 
 
 def info(pretty=False, best=False):
+    # type: (bool, bool) -> InfoDict
     """
     Return certain machine-readable information items about the current OS
     distribution in a dictionary, as shown in the following example:
@@ -429,6 +490,7 @@ def info(pretty=False, best=False):
 
 
 def os_release_info():
+    # type: () -> Dict[str, str]
     """
     Return a dictionary containing key-value pairs for the information items
     from the os-release file data source of the current OS distribution.
@@ -439,6 +501,7 @@ def os_release_info():
 
 
 def lsb_release_info():
+    # type: () -> Dict[str, str]
     """
     Return a dictionary containing key-value pairs for the information items
     from the lsb_release command data source of the current OS distribution.
@@ -450,6 +513,7 @@ def lsb_release_info():
 
 
 def distro_release_info():
+    # type: () -> Dict[str, str]
     """
     Return a dictionary containing key-value pairs for the information items
     from the distro release file data source of the current OS distribution.
@@ -460,6 +524,7 @@ def distro_release_info():
 
 
 def uname_info():
+    # type: () -> Dict[str, str]
     """
     Return a dictionary containing key-value pairs for the information items
     from the distro release file data source of the current OS distribution.
@@ -468,6 +533,7 @@ def uname_info():
 
 
 def os_release_attr(attribute):
+    # type: (str) -> str
     """
     Return a single named information item from the os-release file data source
     of the current OS distribution.
@@ -487,6 +553,7 @@ def os_release_attr(attribute):
 
 
 def lsb_release_attr(attribute):
+    # type: (str) -> str
     """
     Return a single named information item from the lsb_release command output
     data source of the current OS distribution.
@@ -507,6 +574,7 @@ def lsb_release_attr(attribute):
 
 
 def distro_release_attr(attribute):
+    # type: (str) -> str
     """
     Return a single named information item from the distro release file
     data source of the current OS distribution.
@@ -526,6 +594,7 @@ def distro_release_attr(attribute):
 
 
 def uname_attr(attribute):
+    # type: (str) -> str
     """
     Return a single named information item from the distro release file
     data source of the current OS distribution.
@@ -542,19 +611,26 @@ def uname_attr(attribute):
     return _distro.uname_attr(attribute)
 
 
-class cached_property(object):
-    """A version of @property which caches the value.  On access, it calls the
-    underlying function and sets the value in `__dict__` so future accesses
-    will not re-call the property.
-    """
-    def __init__(self, f):
-        self._fname = f.__name__
-        self._f = f
+try:
+    from functools import cached_property
+except ImportError:
+    # Python < 3.8
+    class cached_property(object):  # type: ignore
+        """A version of @property which caches the value.  On access, it calls the
+        underlying function and sets the value in `__dict__` so future accesses
+        will not re-call the property.
+        """
+
+        def __init__(self, f):
+            # type: (Callable[[Any], Any]) -> None
+            self._fname = f.__name__
+            self._f = f
 
-    def __get__(self, obj, owner):
-        assert obj is not None, 'call {} on an instance'.format(self._fname)
-        ret = obj.__dict__[self._fname] = self._f(obj)
-        return ret
+        def __get__(self, obj, owner):
+            # type: (Any, Type[Any]) -> Any
+            assert obj is not None, "call {} on an instance".format(self._fname)
+            ret = obj.__dict__[self._fname] = self._f(obj)
+            return ret
 
 
 class LinuxDistribution(object):
@@ -575,11 +651,15 @@ class LinuxDistribution(object):
     lsb_release command.
     """
 
-    def __init__(self,
-                 include_lsb=True,
-                 os_release_file='',
-                 distro_release_file='',
-                 include_uname=True):
+    def __init__(
+        self,
+        include_lsb=True,
+        os_release_file="",
+        distro_release_file="",
+        include_uname=True,
+        root_dir=None,
+    ):
+        # type: (bool, str, str, bool, Optional[str]) -> None
         """
         The initialization method of this class gathers information from the
         available data sources, and stores that in private instance attributes.
@@ -618,6 +698,9 @@ class LinuxDistribution(object):
           the program execution path the data source for the uname command will
           be empty.
 
+        * ``root_dir`` (string): The absolute path to the root directory to use
+          to find distro-related information files.
+
         Public instance attributes:
 
         * ``os_release_file`` (string): The path name of the
@@ -647,28 +730,50 @@ class LinuxDistribution(object):
         * :py:exc:`UnicodeError`: A data source has unexpected characters or
           uses an unexpected encoding.
         """
-        self.os_release_file = os_release_file or \
-            os.path.join(_UNIXCONFDIR, _OS_RELEASE_BASENAME)
-        self.distro_release_file = distro_release_file or ''  # updated later
+        self.root_dir = root_dir
+        self.etc_dir = os.path.join(root_dir, "etc") if root_dir else _UNIXCONFDIR
+        self.usr_lib_dir = (
+            os.path.join(root_dir, "usr/lib") if root_dir else _UNIXUSRLIBDIR
+        )
+
+        if os_release_file:
+            self.os_release_file = os_release_file
+        else:
+            etc_dir_os_release_file = os.path.join(self.etc_dir, _OS_RELEASE_BASENAME)
+            usr_lib_os_release_file = os.path.join(
+                self.usr_lib_dir, _OS_RELEASE_BASENAME
+            )
+
+            # NOTE: The idea is to respect order **and** have it set
+            #       at all times for API backwards compatibility.
+            if os.path.isfile(etc_dir_os_release_file) or not os.path.isfile(
+                usr_lib_os_release_file
+            ):
+                self.os_release_file = etc_dir_os_release_file
+            else:
+                self.os_release_file = usr_lib_os_release_file
+
+        self.distro_release_file = distro_release_file or ""  # updated later
         self.include_lsb = include_lsb
         self.include_uname = include_uname
 
     def __repr__(self):
-        """Return repr of all info
-        """
-        return \
-            "LinuxDistribution(" \
-            "os_release_file={self.os_release_file!r}, " \
-            "distro_release_file={self.distro_release_file!r}, " \
-            "include_lsb={self.include_lsb!r}, " \
-            "include_uname={self.include_uname!r}, " \
-            "_os_release_info={self._os_release_info!r}, " \
-            "_lsb_release_info={self._lsb_release_info!r}, " \
-            "_distro_release_info={self._distro_release_info!r}, " \
-            "_uname_info={self._uname_info!r})".format(
-                self=self)
+        # type: () -> str
+        """Return repr of all info"""
+        return (
+            "LinuxDistribution("
+            "os_release_file={self.os_release_file!r}, "
+            "distro_release_file={self.distro_release_file!r}, "
+            "include_lsb={self.include_lsb!r}, "
+            "include_uname={self.include_uname!r}, "
+            "_os_release_info={self._os_release_info!r}, "
+            "_lsb_release_info={self._lsb_release_info!r}, "
+            "_distro_release_info={self._distro_release_info!r}, "
+            "_uname_info={self._uname_info!r})".format(self=self)
+        )
 
     def linux_distribution(self, full_distribution_name=True):
+        # type: (bool) -> Tuple[str, str, str]
         """
         Return information about the OS distribution that is compatible
         with Python's :func:`platform.linux_distribution`, supporting a subset
@@ -679,92 +784,102 @@ class LinuxDistribution(object):
         return (
             self.name() if full_distribution_name else self.id(),
             self.version(),
-            self.codename()
+            self.codename(),
         )
 
     def id(self):
+        # type: () -> str
         """Return the distro ID of the OS distribution, as a string.
 
         For details, see :func:`distro.id`.
         """
+
         def normalize(distro_id, table):
-            distro_id = distro_id.lower().replace(' ', '_')
+            # type: (str, Dict[str, str]) -> str
+            distro_id = distro_id.lower().replace(" ", "_")
             return table.get(distro_id, distro_id)
 
-        distro_id = self.os_release_attr('id')
+        distro_id = self.os_release_attr("id")
         if distro_id:
             return normalize(distro_id, NORMALIZED_OS_ID)
 
-        distro_id = self.lsb_release_attr('distributor_id')
+        distro_id = self.lsb_release_attr("distributor_id")
         if distro_id:
             return normalize(distro_id, NORMALIZED_LSB_ID)
 
-        distro_id = self.distro_release_attr('id')
+        distro_id = self.distro_release_attr("id")
         if distro_id:
             return normalize(distro_id, NORMALIZED_DISTRO_ID)
 
-        distro_id = self.uname_attr('id')
+        distro_id = self.uname_attr("id")
         if distro_id:
             return normalize(distro_id, NORMALIZED_DISTRO_ID)
 
-        return ''
+        return ""
 
     def name(self, pretty=False):
+        # type: (bool) -> str
         """
         Return the name of the OS distribution, as a string.
 
         For details, see :func:`distro.name`.
         """
-        name = self.os_release_attr('name') \
-            or self.lsb_release_attr('distributor_id') \
-            or self.distro_release_attr('name') \
-            or self.uname_attr('name')
+        name = (
+            self.os_release_attr("name")
+            or self.lsb_release_attr("distributor_id")
+            or self.distro_release_attr("name")
+            or self.uname_attr("name")
+        )
         if pretty:
-            name = self.os_release_attr('pretty_name') \
-                or self.lsb_release_attr('description')
+            name = self.os_release_attr("pretty_name") or self.lsb_release_attr(
+                "description"
+            )
             if not name:
-                name = self.distro_release_attr('name') \
-                       or self.uname_attr('name')
+                name = self.distro_release_attr("name") or self.uname_attr("name")
                 version = self.version(pretty=True)
                 if version:
-                    name = name + ' ' + version
-        return name or ''
+                    name = name + " " + version
+        return name or ""
 
     def version(self, pretty=False, best=False):
+        # type: (bool, bool) -> str
         """
         Return the version of the OS distribution, as a string.
 
         For details, see :func:`distro.version`.
         """
         versions = [
-            self.os_release_attr('version_id'),
-            self.lsb_release_attr('release'),
-            self.distro_release_attr('version_id'),
-            self._parse_distro_release_content(
-                self.os_release_attr('pretty_name')).get('version_id', ''),
+            self.os_release_attr("version_id"),
+            self.lsb_release_attr("release"),
+            self.distro_release_attr("version_id"),
+            self._parse_distro_release_content(self.os_release_attr("pretty_name")).get(
+                "version_id", ""
+            ),
             self._parse_distro_release_content(
-                self.lsb_release_attr('description')).get('version_id', ''),
-            self.uname_attr('release')
+                self.lsb_release_attr("description")
+            ).get("version_id", ""),
+            self.uname_attr("release"),
         ]
-        version = ''
+        version = ""
         if best:
             # This algorithm uses the last version in priority order that has
             # the best precision. If the versions are not in conflict, that
             # does not matter; otherwise, using the last one instead of the
             # first one might be considered a surprise.
             for v in versions:
-                if v.count(".") > version.count(".") or version == '':
+                if v.count(".") > version.count(".") or version == "":
                     version = v
         else:
             for v in versions:
-                if v != '':
+                if v != "":
                     version = v
                     break
         if pretty and version and self.codename():
-            version = '{0} ({1})'.format(version, self.codename())
+            version = "{0} ({1})".format(version, self.codename())
         return version
 
     def version_parts(self, best=False):
+        # type: (bool) -> Tuple[str, str, str]
         """
         Return the version of the OS distribution, as a tuple of version
         numbers.
@@ -773,14 +888,15 @@ class LinuxDistribution(object):
         """
         version_str = self.version(best=best)
         if version_str:
-            version_regex = re.compile(r'(\d+)\.?(\d+)?\.?(\d+)?')
+            version_regex = re.compile(r"(\d+)\.?(\d+)?\.?(\d+)?")
             matches = version_regex.match(version_str)
             if matches:
                 major, minor, build_number = matches.groups()
-                return major, minor or '', build_number or ''
-        return '', '', ''
+                return major, minor or "", build_number or ""
+        return "", "", ""
 
     def major_version(self, best=False):
+        # type: (bool) -> str
         """
         Return the major version number of the current distribution.
 
@@ -789,6 +905,7 @@ class LinuxDistribution(object):
         return self.version_parts(best)[0]
 
     def minor_version(self, best=False):
+        # type: (bool) -> str
         """
         Return the minor version number of the current distribution.
 
@@ -797,6 +914,7 @@ class LinuxDistribution(object):
         return self.version_parts(best)[1]
 
     def build_number(self, best=False):
+        # type: (bool) -> str
         """
         Return the build number of the current distribution.
 
@@ -805,14 +923,16 @@ class LinuxDistribution(object):
         return self.version_parts(best)[2]
 
     def like(self):
+        # type: () -> str
         """
         Return the IDs of distributions that are like the OS distribution.
 
         For details, see :func:`distro.like`.
         """
-        return self.os_release_attr('id_like') or ''
+        return self.os_release_attr("id_like") or ""
 
     def codename(self):
+        # type: () -> str
         """
         Return the codename of the OS distribution.
 
@@ -821,13 +941,16 @@ class LinuxDistribution(object):
         try:
             # Handle os_release specially since distros might purposefully set
             # this to empty string to have no codename
-            return self._os_release_info['codename']
+            return self._os_release_info["codename"]
         except KeyError:
-            return self.lsb_release_attr('codename') \
-                or self.distro_release_attr('codename') \
-                or ''
+            return (
+                self.lsb_release_attr("codename")
+                or self.distro_release_attr("codename")
+                or ""
+            )
 
     def info(self, pretty=False, best=False):
+        # type: (bool, bool) -> InfoDict
         """
         Return certain machine-readable information about the OS
         distribution.
@@ -840,13 +963,14 @@ class LinuxDistribution(object):
             version_parts=dict(
                 major=self.major_version(best),
                 minor=self.minor_version(best),
-                build_number=self.build_number(best)
+                build_number=self.build_number(best),
             ),
             like=self.like(),
             codename=self.codename(),
         )
 
     def os_release_info(self):
+        # type: () -> Dict[str, str]
         """
         Return a dictionary containing key-value pairs for the information
         items from the os-release file data source of the OS distribution.
@@ -856,6 +980,7 @@ class LinuxDistribution(object):
         return self._os_release_info
 
     def lsb_release_info(self):
+        # type: () -> Dict[str, str]
         """
         Return a dictionary containing key-value pairs for the information
         items from the lsb_release command data source of the OS
@@ -866,6 +991,7 @@ class LinuxDistribution(object):
         return self._lsb_release_info
 
     def distro_release_info(self):
+        # type: () -> Dict[str, str]
         """
         Return a dictionary containing key-value pairs for the information
         items from the distro release file data source of the OS
@@ -876,6 +1002,7 @@ class LinuxDistribution(object):
         return self._distro_release_info
 
     def uname_info(self):
+        # type: () -> Dict[str, str]
         """
         Return a dictionary containing key-value pairs for the information
         items from the uname command data source of the OS distribution.
@@ -885,43 +1012,48 @@ class LinuxDistribution(object):
         return self._uname_info
 
     def os_release_attr(self, attribute):
+        # type: (str) -> str
         """
         Return a single named information item from the os-release file data
         source of the OS distribution.
 
         For details, see :func:`distro.os_release_attr`.
         """
-        return self._os_release_info.get(attribute, '')
+        return self._os_release_info.get(attribute, "")
 
     def lsb_release_attr(self, attribute):
+        # type: (str) -> str
         """
         Return a single named information item from the lsb_release command
         output data source of the OS distribution.
 
         For details, see :func:`distro.lsb_release_attr`.
         """
-        return self._lsb_release_info.get(attribute, '')
+        return self._lsb_release_info.get(attribute, "")
 
     def distro_release_attr(self, attribute):
+        # type: (str) -> str
         """
         Return a single named information item from the distro release file
         data source of the OS distribution.
 
         For details, see :func:`distro.distro_release_attr`.
         """
-        return self._distro_release_info.get(attribute, '')
+        return self._distro_release_info.get(attribute, "")
 
     def uname_attr(self, attribute):
+        # type: (str) -> str
         """
         Return a single named information item from the uname command
         output data source of the OS distribution.
 
-        For details, see :func:`distro.uname_release_attr`.
+        For details, see :func:`distro.uname_attr`.
         """
-        return self._uname_info.get(attribute, '')
+        return self._uname_info.get(attribute, "")
 
     @cached_property
     def _os_release_info(self):
+        # type: () -> Dict[str, str]
         """
         Get the information items from the specified os-release file.
 
@@ -935,6 +1067,7 @@ class LinuxDistribution(object):
 
     @staticmethod
     def _parse_os_release_content(lines):
+        # type: (TextIO) -> Dict[str, str]
         """
         Parse the lines of an os-release file.
 
@@ -959,7 +1092,7 @@ class LinuxDistribution(object):
         # parsed content is a unicode object. The following fix resolves that
         # (... but it should be fixed in shlex...):
         if sys.version_info[0] == 2 and isinstance(lexer.wordchars, bytes):
-            lexer.wordchars = lexer.wordchars.decode('iso-8859-1')
+            lexer.wordchars = lexer.wordchars.decode("iso-8859-1")
 
         tokens = list(lexer)
         for token in tokens:
@@ -969,37 +1102,38 @@ class LinuxDistribution(object):
             # stripped, etc.), so the tokens are now either:
             # * variable assignments: var=value
             # * commands or their arguments (not allowed in os-release)
-            if '=' in token:
-                k, v = token.split('=', 1)
+            if "=" in token:
+                k, v = token.split("=", 1)
                 props[k.lower()] = v
             else:
                 # Ignore any tokens that are not variable assignments
                 pass
 
-        if 'version_codename' in props:
+        if "version_codename" in props:
             # os-release added a version_codename field.  Use that in
             # preference to anything else Note that some distros purposefully
             # do not have code names.  They should be setting
             # version_codename=""
-            props['codename'] = props['version_codename']
-        elif 'ubuntu_codename' in props:
+            props["codename"] = props["version_codename"]
+        elif "ubuntu_codename" in props:
             # Same as above but a non-standard field name used on older Ubuntus
-            props['codename'] = props['ubuntu_codename']
-        elif 'version' in props:
+            props["codename"] = props["ubuntu_codename"]
+        elif "version" in props:
             # If there is no version_codename, parse it from the version
-            codename = re.search(r'(\(\D+\))|,(\s+)?\D+', props['version'])
-            if codename:
-                codename = codename.group()
-                codename = codename.strip('()')
-                codename = codename.strip(',')
+            match = re.search(r"(\(\D+\))|,(\s+)?\D+", props["version"])
+            if match:
+                codename = match.group()
+                codename = codename.strip("()")
+                codename = codename.strip(",")
                 codename = codename.strip()
                 # codename appears within paranthese.
-                props['codename'] = codename
+                props["codename"] = codename
 
         return props
 
     @cached_property
     def _lsb_release_info(self):
+        # type: () -> Dict[str, str]
         """
         Get the information items from the lsb_release command output.
 
@@ -1008,17 +1142,19 @@ class LinuxDistribution(object):
         """
         if not self.include_lsb:
             return {}
-        with open(os.devnull, 'w') as devnull:
+        with open(os.devnull, "wb") as devnull:
             try:
-                cmd = ('lsb_release', '-a')
+                cmd = ("lsb_release", "-a")
                 stdout = subprocess.check_output(cmd, stderr=devnull)
-            except OSError:  # Command not found
+            # Command not found or lsb_release returned error
+            except (OSError, subprocess.CalledProcessError):
                 return {}
         content = self._to_str(stdout).splitlines()
         return self._parse_lsb_release_content(content)
 
     @staticmethod
     def _parse_lsb_release_content(lines):
+        # type: (Iterable[str]) -> Dict[str, str]
         """
         Parse the output of the lsb_release command.
 
@@ -1033,19 +1169,20 @@ class LinuxDistribution(object):
         """
         props = {}
         for line in lines:
-            kv = line.strip('\n').split(':', 1)
+            kv = line.strip("\n").split(":", 1)
             if len(kv) != 2:
                 # Ignore lines without colon.
                 continue
             k, v = kv
-            props.update({k.replace(' ', '_').lower(): v.strip()})
+            props.update({k.replace(" ", "_").lower(): v.strip()})
         return props
 
     @cached_property
     def _uname_info(self):
-        with open(os.devnull, 'w') as devnull:
+        # type: () -> Dict[str, str]
+        with open(os.devnull, "wb") as devnull:
             try:
-                cmd = ('uname', '-rs')
+                cmd = ("uname", "-rs")
                 stdout = subprocess.check_output(cmd, stderr=devnull)
             except OSError:
                 return {}
@@ -1054,25 +1191,27 @@ class LinuxDistribution(object):
 
     @staticmethod
     def _parse_uname_content(lines):
+        # type: (Sequence[str]) -> Dict[str, str]
         props = {}
-        match = re.search(r'^([^\s]+)\s+([\d\.]+)', lines[0].strip())
+        match = re.search(r"^([^\s]+)\s+([\d\.]+)", lines[0].strip())
         if match:
             name, version = match.groups()
 
             # This is to prevent the Linux kernel version from
             # appearing as the 'best' version on otherwise
             # identifiable distributions.
-            if name == 'Linux':
+            if name == "Linux":
                 return {}
-            props['id'] = name.lower()
-            props['name'] = name
-            props['release'] = version
+            props["id"] = name.lower()
+            props["name"] = name
+            props["release"] = version
         return props
 
     @staticmethod
     def _to_str(text):
+        # type: (Union[bytes, str]) -> str
         encoding = sys.getfilesystemencoding()
-        encoding = 'utf-8' if encoding == 'ascii' else encoding
+        encoding = "utf-8" if encoding == "ascii" else encoding
 
         if sys.version_info[0] >= 3:
             if isinstance(text, bytes):
@@ -1085,6 +1224,7 @@ class LinuxDistribution(object):
 
     @cached_property
     def _distro_release_info(self):
+        # type: () -> Dict[str, str]
         """
         Get the information items from the specified distro release file.
 
@@ -1094,23 +1234,21 @@ class LinuxDistribution(object):
         if self.distro_release_file:
             # If it was specified, we use it and parse what we can, even if
             # its file name or content does not match the expected pattern.
-            distro_info = self._parse_distro_release_file(
-                self.distro_release_file)
+            distro_info = self._parse_distro_release_file(self.distro_release_file)
             basename = os.path.basename(self.distro_release_file)
             # The file name pattern for user-specified distro release files
             # is somewhat more tolerant (compared to when searching for the
             # file), because we want to use what was specified as best as
             # possible.
             match = _DISTRO_RELEASE_BASENAME_PATTERN.match(basename)
-            if 'name' in distro_info \
-               and 'cloudlinux' in distro_info['name'].lower():
-                distro_info['id'] = 'cloudlinux'
+            if "name" in distro_info and "cloudlinux" in distro_info["name"].lower():
+                distro_info["id"] = "cloudlinux"
             elif match:
-                distro_info['id'] = match.group(1)
+                distro_info["id"] = match.group(1)
             return distro_info
         else:
             try:
-                basenames = os.listdir(_UNIXCONFDIR)
+                basenames = os.listdir(self.etc_dir)
                 # We sort for repeatability in cases where there are multiple
                 # distro specific files; e.g. CentOS, Oracle, Enterprise all
                 # containing `redhat-release` on top of their own.
@@ -1120,38 +1258,41 @@ class LinuxDistribution(object):
                 # sure about the *-release files. Check common entries of
                 # /etc for information. If they turn out to not be there the
                 # error is handled in `_parse_distro_release_file()`.
-                basenames = ['SuSE-release',
-                             'arch-release',
-                             'base-release',
-                             'centos-release',
-                             'fedora-release',
-                             'gentoo-release',
-                             'mageia-release',
-                             'mandrake-release',
-                             'mandriva-release',
-                             'mandrivalinux-release',
-                             'manjaro-release',
-                             'oracle-release',
-                             'redhat-release',
-                             'sl-release',
-                             'slackware-version']
+                basenames = [
+                    "SuSE-release",
+                    "arch-release",
+                    "base-release",
+                    "centos-release",
+                    "fedora-release",
+                    "gentoo-release",
+                    "mageia-release",
+                    "mandrake-release",
+                    "mandriva-release",
+                    "mandrivalinux-release",
+                    "manjaro-release",
+                    "oracle-release",
+                    "redhat-release",
+                    "sl-release",
+                    "slackware-version",
+                ]
             for basename in basenames:
                 if basename in _DISTRO_RELEASE_IGNORE_BASENAMES:
                     continue
                 match = _DISTRO_RELEASE_BASENAME_PATTERN.match(basename)
                 if match:
-                    filepath = os.path.join(_UNIXCONFDIR, basename)
+                    filepath = os.path.join(self.etc_dir, basename)
                     distro_info = self._parse_distro_release_file(filepath)
-                    if 'name' in distro_info:
+                    if "name" in distro_info:
                         # The name is always present if the pattern matches
                         self.distro_release_file = filepath
-                        distro_info['id'] = match.group(1)
-                        if 'cloudlinux' in distro_info['name'].lower():
-                            distro_info['id'] = 'cloudlinux'
+                        distro_info["id"] = match.group(1)
+                        if "cloudlinux" in distro_info["name"].lower():
+                            distro_info["id"] = "cloudlinux"
                         return distro_info
             return {}
 
     def _parse_distro_release_file(self, filepath):
+        # type: (str) -> Dict[str, str]
         """
         Parse a distro release file.
 
@@ -1170,11 +1311,12 @@ class LinuxDistribution(object):
         except (OSError, IOError):
             # Ignore not being able to read a specific, seemingly version
             # related file.
-            # See https://github.com/nir0s/distro/issues/162
+            # See https://github.com/python-distro/distro/issues/162
             return {}
 
     @staticmethod
     def _parse_distro_release_content(line):
+        # type: (str) -> Dict[str, str]
         """
         Parse a line from a distro release file.
 
@@ -1185,18 +1327,17 @@ class LinuxDistribution(object):
         Returns:
             A dictionary containing all information items.
         """
-        matches = _DISTRO_RELEASE_CONTENT_REVERSED_PATTERN.match(
-            line.strip()[::-1])
+        matches = _DISTRO_RELEASE_CONTENT_REVERSED_PATTERN.match(line.strip()[::-1])
         distro_info = {}
         if matches:
             # regexp ensures non-None
-            distro_info['name'] = matches.group(3)[::-1]
+            distro_info["name"] = matches.group(3)[::-1]
             if matches.group(2):
-                distro_info['version_id'] = matches.group(2)[::-1]
+                distro_info["version_id"] = matches.group(2)[::-1]
             if matches.group(1):
-                distro_info['codename'] = matches.group(1)[::-1]
+                distro_info["codename"] = matches.group(1)[::-1]
         elif line:
-            distro_info['name'] = line.strip()
+            distro_info["name"] = line.strip()
         return distro_info
 
 
@@ -1204,27 +1345,42 @@ _distro = LinuxDistribution()
 
 
 def main():
+    # type: () -> None
     logger = logging.getLogger(__name__)
     logger.setLevel(logging.DEBUG)
     logger.addHandler(logging.StreamHandler(sys.stdout))
 
     parser = argparse.ArgumentParser(description="OS distro info tool")
     parser.add_argument(
-        '--json',
-        '-j',
-        help="Output in machine readable format",
-        action="store_true")
+        "--json", "-j", help="Output in machine readable format", action="store_true"
+    )
+
+    parser.add_argument(
+        "--root-dir",
+        "-r",
+        type=str,
+        dest="root_dir",
+        help="Path to the root filesystem directory (defaults to /)",
+    )
+
     args = parser.parse_args()
 
+    if args.root_dir:
+        dist = LinuxDistribution(
+            include_lsb=False, include_uname=False, root_dir=args.root_dir
+        )
+    else:
+        dist = _distro
+
     if args.json:
-        logger.info(json.dumps(info(), indent=4, sort_keys=True))
+        logger.info(json.dumps(dist.info(), indent=4, sort_keys=True))
     else:
-        logger.info('Name: %s', name(pretty=True))
-        distribution_version = version(pretty=True)
-        logger.info('Version: %s', distribution_version)
-        distribution_codename = codename()
-        logger.info('Codename: %s', distribution_codename)
+        logger.info("Name: %s", dist.name(pretty=True))
+        distribution_version = dist.version(pretty=True)
+        logger.info("Version: %s", distribution_version)
+        distribution_codename = dist.codename()
+        logger.info("Codename: %s", distribution_codename)
 
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     main()
diff --git a/src/pip/_vendor/distro.pyi b/src/pip/_vendor/distro.pyi
deleted file mode 100644
index c7ea94b37..000000000
--- a/src/pip/_vendor/distro.pyi
+++ /dev/null
@@ -1 +0,0 @@
-from distro import *
\ No newline at end of file
diff --git a/src/pip/_vendor/vendor.txt b/src/pip/_vendor/vendor.txt
index 73e493434..ea0c213e7 100644
--- a/src/pip/_vendor/vendor.txt
+++ b/src/pip/_vendor/vendor.txt
@@ -2,7 +2,7 @@ appdirs==1.4.4
 CacheControl==0.12.6
 colorama==0.4.4
 distlib==0.3.2
-distro==1.5.0
+distro==1.6.0
 html5lib==1.1
 msgpack==1.0.2
 packaging==21.0