The documentation says the config file for Windows is %HOME%\pip\pip.ini, but pip actually looks for %APPDATA%\pip\pip.ini. It only uses %HOME% if %APPDATA% isn't set.
On Windows pip should look for its config file in the 'pip' subdirectory of
the user's Home directory (as returned by os.path.expanduser('~')). The
%APPDATA% directory is hidden by default, so it seems it's not intended for
users to modify it directly.
The fix is just a matter of removing one line from locations.py. I'm attaching
Original Comment By: davis
+1 for this simple fix
remove special case for user_dir on win32 platform. fixes #82