Unknown wheel version with flit 3.2.0

[RMeli]

I use flit in GitHub actions and there seem to be a problem with flit version 3.2.0:

$ flit build

Found 205 files tracked in git                                                                                            I-flit.sdist
Using setup.py from repository, not generating setup.py                                                                   W-flit.sdist
Built sdist: dist/spyrmsd-0.5.0.tar.gz                                                                               I-flit_core.sdist
Copying package file(s) from /var/folders/r0/2dklzyn57d59g13_21b6kt7h0000gp/T/tmpymefc7np/spyrmsd-0.5.0/spyrmsd      I-flit_core.wheel
Writing metadata files                                                                                               I-flit_core.wheel
Writing the record of files                                                                                          I-flit_core.wheel
Built wheel: dist/spyrmsd-0+unknown-py3-none-any.whl                                                                 I-flit_core.wheel

As you can see, the wheel version is unknown: dist/spyrmsd-0+unknown-py3-none-any.whl. This is problematic since flit publish fails with the following error:

$flit publish

[...]

requests.exceptions.HTTPError: 400 Client Error: '0+unknown' is an invalid value for Version. Error: Can't use PEP 440 local versions. See https://packaging.python.org/specifications/core-metadata for more information. for url: https://upload.pypi.org/legacy/

If I downgrade to flit version 3.1.0 the problem no longer persists:

$ flit build # with flit 3.1.0

Found 205 files tracked in git                                                                                            I-flit.sdist
Using setup.py from repository, not generating setup.py                                                                   W-flit.sdist
Built sdist: dist/spyrmsd-0.5.0.tar.gz                                                                               I-flit_core.sdist
Copying package file(s) from /var/folders/r0/2dklzyn57d59g13_21b6kt7h0000gp/T/tmp0llve0g8/spyrmsd-0.5.0/spyrmsd      I-flit_core.wheel
Writing metadata files                                                                                               I-flit_core.wheel
Writing the record of files                                                                                          I-flit_core.wheel
Built wheel: dist/spyrmsd-0.5.0-py3-none-any.whl                                                                     I-flit_core.wheel

[takluyver]

The 0+unknown seems to come from your _version.py. I've never been a fan of those tools that try to figure out the version number when the module is loaded.

[RMeli]

Hi @takluyver , thank you for looking into this. The 0+unknown comes indeed from _version.py, but what it is very puzzling is that the version on my local installation is correct, and flit used to work with versioneer ins previous versions. Did something changed in flit==3.2.0 that makes it incompatible with automatic versioning tools? flit==3.1.0 works as expected, as did previous versions.

[takluyver]

I guess something must have changed, but there's nothing obvious in the release notes that would affect that. Maybe I missed something out of the release notes. You could also look through the complete diff or try bisecting it.

[RMeli]

This is unfortunately still an issue: https://github.com/RMeli/spyrmsd/actions/runs/6126040044/job/16629237158