sysconfig installation scheme change breaks stuff

[Dan Streetman]

the 3.10 version of python in debian and ubuntu appears to have changed its installation scheme from 'posix_prefix' to the debian-specific 'posix_local', which breaks things, for example meson is no longer buildable:
https://launchpadlibrarian.net/595057055/buildlog_ubuntu-jammy-amd64.meson_0.61.2-1_BUILDING.txt.gz

I suspect the problem is an incomplete patching of python to correctly use the 'local' path, as (for example) distutils/setuptools doesn't appear to be using the new 'local' path (in the above build output, search for 'test_meson_installed' to see the failure of meson getting installed to the sysconfig 'scripts' path, which is now '/usr/local/bin' instead of '/usr/bin').

[Dan Streetman (ddstreet)]

I suspect this might be a rather critical problem to fix before jammy releases? Just guessing though.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Stefano Rivera (stefanor)]

This is by design. See: https://lists.debian.org/debian-python/2022/03/msg00039.html

There was a Debian bug tracking the effect on Meson, apparently the issue was fixed upstream.
See: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1009097#32

[Dan Streetman (ddstreet)]

> This is by design. See: https://lists.debian.org/debian-python/2022/03/msg00039.html

I get that, my point is it doesn't seem to be done correctly.

> There was a Debian bug tracking the effect on Meson, apparently the issue was fixed upstream.
> See: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1009097#32

I think it's more likely this failing test was fixed upstream by:
https://github.com/mesonbuild/meson/commit/54808cd39b765f5553c3c6ae49e5ef14b5290b08

However, that test isn't the real problem; see how upstream meson 'fixed' this:

https://github.com/mesonbuild/meson/commit/a2079939de2d1d271e5ea7f23c3656a73e325728

You sure nothing else needs to be done for this in Debian?

[Dan Streetman (ddstreet)]

> You sure nothing else needs to be done for this in Debian?

To be specific: are you sure that it's better to leave {base} set to /usr and prefix the various paths with 'local'? Any package build that chooses a different {base} will then still have things put into their custom {base}/local/... which might not be what they expect (certainly wasn't what meson expected)?

[Benjamin Bach (benjaoming)]

This also affects the layout of new virtual environments, which causes many tools to not locate Python and pip executables.

This breaks popular tools like pre-commit and virtualenvwrapper because they assume that the virtualenv looks like the posix_prefix.

See:
https://github.com/pre-commit/pre-commit/issues/2336
https://github.com/bernardobarreto/virtualenvwrapper/issues/20

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "venv-patch.diff" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

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