main/python3: Change user install location to /usr/local (to avoid externally-managed)

• https://packaging.python.org/en/latest/specifications/externally-managed-environments/

• https://src.fedoraproject.org/rpms/python3.12/blob/rawhide/f/00251-change-user-install-location.patch

  Set values of base and platbase in sysconfig from /usr to /usr/local when RPM build is not detected to make pip and similar tools install into separate location.

  Fedora Change: https://fedoraproject.org/wiki/Changes/Making_sudo_pip_safe

  We've tried to rework in Fedora 36/Python 3.10 to follow https://bugs.python.org/issue43976 but we have identified serious problems with that approach, see https://bugzilla.redhat.com/2026979 or https://bugzilla.redhat.com/2097183

  pypa/distutils integration: https://github.com/pypa/distutils/pull/70

We use the same approach in Ruby and Lua – gem and luarocks install packages to /usr/local by default to not clash with apk-managed packages.

We probably don’t need so complicated way as Fedora because we normally don’t run pip install inside APKBUILDs.

added lang:python label

marked this issue as related to #14617 (closed)

changed the description

can this wait til after 3.20 release?

Well, I originally wanted this for v3.20 because it’s really very annoying for CI and container images in general, but it seems we’re going to have to think this through more.

this has the same issue as not having external-managed at all - user-installed packages will clash with the distro-installed ones, causing side effects such as having the same Python module with two mismatching versions and potentially breaking system packages; the only foolproof way is to either remove the externally-managed restriction altogether and not use distro python packages ( which is pretty much impossible given how much stuff depends on py3-* modules ), or install pip packages in a venv that doesn't use system packages ( or uses them only when the version matches, but i'm not sure if --system-site-packages venv option does that )