[Python-modules-team] Bug#876145: python-pip: pip install --system as non-root shouldn't default --ignore-installed

[Kjell Braden]

On Mon, 18 Sep 2017 21:21:31 -0400 Peter Amstutz
<peter.amstutz at curoverse.com> wrote:
> When running "pip install --system" as a non-root user, the change in
> set_user_default.patch forces the --ignore-installed flag to be enabled.
> 
> This has the effect of breaking pip for use cases that install packages as non-
> root but don't use --user or virtualenv.

This also means that if I install a package with --user it will have any
dependencies installed in the user's home, even if they already exist in
the system directories (i.e. installed through apt) and satisfy all
requirements - with no possible workaround, other than reverting this patch.

Also note that the virtualenv detection fails on python3 venv, breaking
the --system-site-packages option.

Even more reason (see #830892) to drop the patch in question.