[Backport release-25.11] buildPython*: support fixed-point arguments

[nixpkgs-ci]

Bot-based backport to release-25.11, triggered by a label in #271387.

Before merging, ensure that this backport is acceptable for the release.

Even as a non-committer, if you find that it is not acceptable, leave a comment.

Tip

If you maintain all packages touched by this pull request, and they are all located under pkgs/by-name/*, you can comment @NixOS/nixpkgs-merge-bot merge to automatically merge this PR using the nixpkgs-merge-bot.

[ShamrockLee]

This requires porting the buildPythonPackage.override { stdenv = customStdenv; } interface.

[mdaniels5757]

@ShamrockLee are you talking about #271762? That has been present in 25.11 since its inception.

[mdaniels5757]

Regardless of the answer, I think waiting a day or two before backporting seems prudent, especially if there might be a change needed for #477007.

[ShamrockLee]

@ShamrockLee are you talking about #271762? That has been present in 25.11 since its inception.

Just found that all the fix-up PRs for PR #271762 are already backported to release-25.11.

[mdaniels5757]

There seems to be no breakage on master, and people are beginning to make changes on master that use this. Absent any reason to not merge this, I intend to merge in a couple of hours, and then we can merge follow-ups as they happen.

[mdaniels5757]

Actually #477098 is giving me pause.