Let a changelog with a release level be found - #2100

A changelog whose version carries a release level — WinPythondot-64bit-3.14.7.1b1.md — is invisible to find_previous_version, so the history of the next release is compared against the wrong baseline.

The cause

find_previous_version reads the previous release out of the file names in changelogs/, through ([0-9\.]+)\.(txt|md). A version with a release level has letters in it, so it matches nothing and is skipped.

The ordering never needed anything — PEP 440 already places them correctly:

3.14.7.0  <  3.14.7.1b1  <  3.14.7.1

Only the name pattern was wrong. Names now go to the version parser, and whatever does not parse as a version is skipped, which drops the _History.md companions by the same rule rather than relying on the digit class to exclude them.

This is live, not hypothetical

WinPythondot-64bit-3.9.0.0b1.md has been in changelogs/ for years, unseen. Against the real directory:

So 3.9.0.0's history was diffed against 3.8.10.0 and reported the beta's changes a second time. Nothing else in the directory answers differently.

copy_changelogs carried the same pattern and now selects on the parsed version instead of a string prefix, so a level travels with its cycle and 3.1 cannot pick up 3.15.

Why now

The cycle build (#2098) will start producing changelogs for beta cycles, and the file name is the only thing carrying the version. This has to work before a b1 is published, whichever way the naming question is settled — the fix is correct on its own terms either way.

Testing

tests/test_diff_versions.py, 20 tests on synthetic directories: level ordering in both directions, the five levels WinPython has used (b1 b2 rc1 a1 post1), _History never being picked, .txt changelogs still counting, the documented "nothing earlier returns the target itself" fallback, and the separations that matter — dot/slim, dot/dotf, flavored/unflavored, 32/64 bit.

Mutation-checked: restoring the old pattern fails exactly the 8 level-related tests and leaves the other 12 green. Full suite 183 passed.

Independent of #2099 — no shared files, no ordering constraint.

🤖 Generated with Claude Code

https://claude.ai/code/session_01MBk5k7WdpPvx4SUFyEk3U3