pypa/pip — pull request #705 by qwcode (2012-10-18 06:08:04+00:00)
Title: --user installs work properly with --upgrade

this in in response to pull #704.
this fixes the same problem, but also provides a test.
#704 fixes the issue via the "_permitted" check during uninstallation.
This pull is more direct, in that it doesn't allow the global install to be a conflict in the first place, which it shouldn't be during any --user install.