Editable installs broken with pip 22.1

[bollwyvl]

Problem

All CI jobs will probably fail right now if using pip 22.1 with the tell-tale error of:

pip._vendor.packaging.markers.UndefinedEnvironmentName: 'extra' does not exist in evaluation environment.

References

• observed on #724
• probably due to https://github.com/pypa/pip/issues/11110
  • it's suggested the "clever" _version.py and version_info stuff triggers flit to do more install than it's ready to do...

Approaches

• wait for it to resolve itself
  • pip or flit might fix something
• accept dupliaction
  • in pyproject.toml
    • remove version from dynamic
    • add explicit version there
  • add a test, etc. to verify the versions are in sync
• ???

[bollwyvl]

Verified that #726 "fixes" the issue, but open to other approaches to unstick things.

[bollwyvl]

It appears this will indeed be fixed upstream by pip...

[vidartf]

Did the switch to Hatch in #728 fix this?

[bollwyvl]

Probably? I think if CI is passing, then it will work.

I'm waiting until a new pip !=22.1.0 version shows up before assessing: a lot of things got broken by these changes, and am not sure flipping rapidly between build backends helps much.