Fix traceback.format_exc call

format_exc takes only one argument, limit which should be an integer.
python 2 seems more lenient than python 3 on that point.

mistake introduced in commit 3148b967a

2 files changed, 28 insertions, 2 deletions

diff --git a/pip/req/req_install.py b/pip/req/req_install.py
index 83b817a44..4ed58f29c 100644
--- a/pip/req/req_install.py
+++ b/pip/req/req_install.py
@@ -344,11 +344,11 @@ class InstallRequirement(object):
         assert self.source_dir, "No source dir for %s" % self
         try:
             import setuptools  # noqa
-        except ImportError as e:
+        except ImportError:
             if get_installed_version('setuptools') is None:
                 add_msg = "Please install setuptools."
             else:
-                add_msg = traceback.format_exc(e)
+                add_msg = traceback.format_exc()
             # Setuptools is not available
             raise InstallationError(
                 "Could not import setuptools which is required to "
diff --git a/tests/functional/test_install.py b/tests/functional/test_install.py
index 47ca38cd4..c54fe7e3c 100644
--- a/tests/functional/test_install.py
+++ b/tests/functional/test_install.py
@@ -30,6 +30,32 @@ def test_without_setuptools(script, data):
         "source distribution."
         in result.stderr
     )
+    assert "Please install setuptools" in result.stderr
+
+
+def test_with_setuptools_and_import_error(script, data):
+    # Make sure we get an ImportError while importing setuptools
+    setuptools_init_path = script.site_packages_path.join(
+        "setuptools", "__init__.py")
+    with open(setuptools_init_path, 'a') as f:
+        f.write('\nraise ImportError("toto")')
+
+    result = script.run(
+        "python", "-c",
+        "import pip; pip.main(["
+        "'install', "
+        "'INITools==0.2', "
+        "'-f', '%s', "
+        "'--no-binary=:all:'])" % data.packages,
+        expect_error=True,
+    )
+    assert (
+        "Could not import setuptools which is required to install from a "
+        "source distribution."
+        in result.stderr
+    )
+    assert "Traceback " in result.stderr
+    assert "ImportError: toto" in result.stderr
 
 
 def test_pip_second_command_line_interface_works(script, data):