This looks reasonable to me but I don't know this code enough to review it.

However, the fix will require bumping the PYC magic number in 3.14.0rc2 :( Heads up,@hugovk

The code changes look good to me.

I think this needs a separate pyc magic number bump for the backport.
On main: 3654 -> 3655, and for 3.14: 3624 -> 3625.

Thanks@iritkatriel for the PR 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖

Sorry,@iritkatriel, I could not cleanly backport this to3.14 due to a conflict.
Please backport usingcherry_picker on command line.

cherry_picker 1f2026b8a239b3169c0cad0157eb08358152b4c1 3.14

GH-137427 is a backport of this pull request to the3.14 branch.

However, the fix will require bumping the PYC magic number in 3.14.0rc2 :( Heads up,@hugovk

I was pointed at this PR with a message saying "a fix for 3.14.0rc2 may require telling projects that already cut a release to redo that". On closer inspection, that doesn't seem to be the case. The ABI doesn't change here, and packages on PyPI shouldn't contain.pyc code (unless some bad legacy build config in a package explicitly includes.pyc code in wheels). And at install time,.pyc files with an older bytecode magic number should be ignored and be regenerated. So there is no serious impact here, right?

I know that Fedora builds .pycs, installs them as root so users can't update them, and the more locked-down settings generate security alerts when users attempt to overwrite system files.
Not sure how other redistributors are affected, but I assume this is close to the worst case.

Ah of course, distros and other deployment methods that install with root/elevated privileges, thanks@encukou. A bit of digging turns up#73700, which seems like it wasn't much fun for affected redistributors.

There hopefully won't be many distros that distribute packages before the final 3.14.0 release; I believe Fedora is fairly exceptional in doing that. Same for sysadmins installing on multi-user systems, that should be rare pre-3.14.0-final.

FYI We'll do an early rc2 with this and add an rc3 next month:

• https://discuss.python.org/t/early-3-14-0-rc2-and-extra-rc3/102151