Merge pull request #8718 from uranusjr/pyvenv-cfg-encoding

Always use UTF-8 to read pyvenv.cfg

news/8717.bugfix

@@ -0,0 +1 @@
+Always use UTF-8 to read ``pyvenv.cfg`` to match the built-in ``venv``.

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