Evaluation install fails since the recent flit migration

[martinRenou]

Since the recent flit migration #1767, install nbconvert with pip install -e . fails with:

ERROR: Exception:
Traceback (most recent call last):
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/cli/base_command.py", line 167, in exc_logging_wrapper
    status = run_func(*args)
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/cli/req_command.py", line 205, in wrapper
    return func(self, options, args)
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/commands/install.py", line 340, in run
    requirement_set = resolver.resolve(
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/resolution/resolvelib/resolver.py", line 75, in resolve
    collected = self.factory.collect_root_requirements(root_reqs)
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/resolution/resolvelib/factory.py", line 506, in collect_root_requirements
    req = self._make_requirement_from_install_req(
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/resolution/resolvelib/factory.py", line 468, in _make_requirement_from_install_req
    cand = self._make_candidate_from_link(
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/resolution/resolvelib/factory.py", line 188, in _make_candidate_from_link
    self._editable_candidate_cache[link] = EditableCandidate(
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/resolution/resolvelib/candidates.py", line 316, in __init__
    super().__init__(
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/resolution/resolvelib/candidates.py", line 161, in __init__
    self.dist = self._prepare()
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/resolution/resolvelib/candidates.py", line 230, in _prepare
    dist = self._prepare_distribution()
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/resolution/resolvelib/candidates.py", line 326, in _prepare_distribution
    return self._factory.preparer.prepare_editable_requirement(self._ireq)
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/operations/prepare.py", line 543, in prepare_editable_requirement
    dist = _get_prepared_distribution(
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/operations/prepare.py", line 57, in _get_prepared_distribution
    abstract_dist.prepare_distribution_metadata(finder, build_isolation)
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/distributions/sdist.py", line 45, in prepare_distribution_metadata
    self._install_build_reqs(finder)
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/distributions/sdist.py", line 114, in _install_build_reqs
    conflicting, missing = self.req.build_env.check_requirements(build_reqs)
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_internal/build_env.py", line 178, in check_requirements
    if req.marker is not None and not req.marker.evaluate():
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_vendor/packaging/markers.py", line 304, in evaluate
    return _evaluate_markers(self._markers, current_environment)
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_vendor/packaging/markers.py", line 234, in _evaluate_markers
    lhs_value = _get_env(environment, lhs.value)
  File "/home/martin/micromamba/envs/nbconvert/lib/python3.10/site-packages/pip/_vendor/packaging/markers.py", line 215, in _get_env
    raise UndefinedEnvironmentName(
pip._vendor.packaging.markers.UndefinedEnvironmentName: 'extra' does not exist in evaluation environment.

Is there anything I need to do apart from installing flit?

@blink1073 are we moving away from jupyter_packaging and using flit instead now?

[blink1073]

I'm working on a hatch plugin to replace jupyter-packaging, cf jupyter/notebook#6425

[martinRenou]

Do you have any clue about what is happening currently with the pip install -e .? I am still getting this UndefinedEnvironmentName: 'extra' does not exist in evaluation environment. error and not able to get a working dev nbconvert.

[maartenbreddels]

I downgraded pip (pip install flit "pip<22") in CI for 1 package, while the other ran fine, not sure why. Could you test this?

[martinRenou]

Thanks for shimming in @maartenbreddels. pip<22 seems to work indeed! It's probably better than me patching my local pip installation (it was actually working too ahah) 😅