Always use UTF-8 to read pyvenv.cfg

2 files changed, 5 insertions, 1 deletions

diff --git a/news/8717.bugfix b/news/8717.bugfix
new file mode 100644
index 000000000..e8c8533c4
--- /dev/null
+++ b/news/8717.bugfix
@@ -0,0 +1 @@
+Always use UTF-8 to read ``pyvenv.cfg`` to match the built-in ``venv``.
diff --git a/src/pip/_internal/utils/virtualenv.py b/src/pip/_internal/utils/virtualenv.py
index 596a69a7d..4a7812873 100644
--- a/src/pip/_internal/utils/virtualenv.py
+++ b/src/pip/_internal/utils/virtualenv.py
@@ -1,5 +1,6 @@
 from __future__ import absolute_import
 
+import io
 import logging
 import os
 import re
@@ -51,7 +52,9 @@ def _get_pyvenv_cfg_lines():
     """
     pyvenv_cfg_file = os.path.join(sys.prefix, 'pyvenv.cfg')
     try:
-        with open(pyvenv_cfg_file) as f:
+        # Although PEP 405 does not specify, the built-in venv module always
+        # writes with UTF-8. (pypa/pip#8717)
+        with io.open(pyvenv_cfg_file, encoding='utf-8') as f:
             return f.read().splitlines()  # avoids trailing newlines
     except IOError:
         return None