Re: Guix's python has pip's user dir in its loadpath

[Maxim Cournoyer <maxim.cournoyer@gmail.com>]

Hello,

Wojtek Kosior <koszko@koszko.org> writes:

>> > I just saw this message and hurried myself up to test the patch to
>> > python-build-system that I made. Unfortunately, it turns out the
>> > "PYTHONNOUSERSITE=1" env var breaks pip which tries to install wheels to
>> > the system site directory and fails due to a read-only filesystem.  
>> 
>> I'm not sure I follow; why would PYTHONNOUSERSITE affect pip?  I thought
>> it should only appear in wrappers of Python executables, not be set in a
>> profile's environment (thus not affecting pip) ?
>
> Indeed. And once I make my change, PYTHONNOUSERSITE gets also placed in
> the wrapper of the `pip` executable.
>
>> Could you share the diff of the patch you tried so far?
>
> I am attaching the patch file.
>
> I was trying to test with
>
>     ./pre-inst-env guix shell -C --network --no-cwd python-xmldiff coreutils python-pip
>     pip install xmldiff==2.4
>     echo > ~/.local/lib/python3.10/site-packages/xmldiff/main.py
>     xmldiff --help
>
> Without my patch, we get an error on 4th line. With my patch, we get
> the "Read-only file system" error on the 2nd line

Neat!  I think maybe we could add a build argument called
e.g. '#:honor-user-site?' to disable the having PYTHONNOUSERSITE=1 in
the wrapper for a few select packages (e.g. pip, virtualenv, probably a
few others that are expected to work with or honor pip user-installed
Python packages).

-- 
Thanks,
Maxim