new importlib-metadata release causes tox to break pip on Python<3.8

[cjw296]

This line:
https://github.com/tox-dev/tox/blob/master/setup.cfg#L41

Causes pip to end up installing invalid dependencies and then barfing about them at runtime:

AssertionError: Traceback (most recent call last):
  File "setup.py", line 10, in <module>
    author_email='[email protected]',
  File "/data/jenkins/shiningpanda/jobs/7ec1442c/virtualenvs/d41d8cd9/lib/python3.6/site-packages/setuptools/__init__.py", line 145, in setup
    return distutils.core.setup(**attrs)
  File "/usr/lib64/python3.6/distutils/core.py", line 134, in setup
    ok = dist.parse_command_line()
  File "/data/jenkins/shiningpanda/jobs/7ec1442c/virtualenvs/d41d8cd9/lib/python3.6/site-packages/setuptools/dist.py", line 707, in parse_command_line
    result = _Distribution.parse_command_line(self)
  File "/usr/lib64/python3.6/distutils/dist.py", line 472, in parse_command_line
    args = self._parse_command_opts(parser, args)
  File "/data/jenkins/shiningpanda/jobs/7ec1442c/virtualenvs/d41d8cd9/lib/python3.6/site-packages/setuptools/dist.py", line 1014, in _parse_command_opts
    nargs = _Distribution._parse_command_opts(self, parser, args)
  File "/usr/lib64/python3.6/distutils/dist.py", line 528, in _parse_command_opts
    cmd_class = self.get_command_class(command)
  File "/data/jenkins/shiningpanda/jobs/7ec1442c/virtualenvs/d41d8cd9/lib/python3.6/site-packages/setuptools/dist.py", line 833, in get_command_class
    ep.require(installer=self.fetch_build_egg)
  File "/data/jenkins/shiningpanda/jobs/7ec1442c/virtualenvs/d41d8cd9/lib/python3.6/site-packages/pkg_resources/__init__.py", line 2465, in require
    items = working_set.resolve(reqs, env, installer, extras=self.extras)
  File "/data/jenkins/shiningpanda/jobs/7ec1442c/virtualenvs/d41d8cd9/lib/python3.6/site-packages/pkg_resources/__init__.py", line 791, in resolve
    raise VersionConflict(dist, req).with_context(dependent_req)
pkg_resources.ContextualVersionConflict: (importlib-metadata 1.1.0 (/data/jenkins/shiningpanda/jobs/7ec1442c/virtualenvs/d41d8cd9/lib/python3.6/site-packages), Requirement.parse('importlib-metadata<1,>=0.12; python_version < "3.8"'), {'tox'})

Honestly, this is arguably a pip bug, since 1.0.0 still meets the requirements, but it's likely more pragmatic to just change the requirement in your setup.cfg to be <2.0.

[gaborbernat]

Closed via #1472

[StingyJack]

I had this error happen quite unexpectedly over the weekend, and spent sunday morning trying to fix it. I resolved it by adding 'importlib-metadata>=0.12,<1' to my setup.py file...

ERROR: tox 3.14.1 has requirement importlib-metadata<1,>=0.12; python_version < "3.8", but you'll have importlib-metadata 1.0.0 which is incompatible.

And now I've started receiving this error a few minutes ago...

ERROR: tox 3.14.2 has requirement importlib-metadata<2,>=1.1.0; python_version < "3.8", but you'll have importlib-metadata 0.23 which is incompatible.

I dont think its right to be using a patch-version increment when jumping a major version of a dependency like that. Time to lock tox on v3.14.1.

[vlizanae]

I'm having a similar issue but now with importlib-metadata 2.0.0:

    ERROR: Command errored out with exit status 1:
     command: /home/vlizana/repos/vlizanae/pyntual/.tox/py36/bin/python -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-req-build-o9i6ucw5/setup.py'"'"'; __file__='"'"'/tmp/pip-req-build-o9i6ucw5/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-pip-egg-info-lwgjlqw7
         cwd: /tmp/pip-req-build-o9i6ucw5/
    Complete output (13 lines):
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-req-build-o9i6ucw5/setup.py", line 52, in <module>
        zip_safe=False,
      File "/home/vlizana/repos/vlizanae/pyntual/.tox/py36/lib/python3.6/site-packages/setuptools/__init__.py", line 162, in setup
        _install_setup_requires(attrs)
      File "/home/vlizana/repos/vlizanae/pyntual/.tox/py36/lib/python3.6/site-packages/setuptools/__init__.py", line 157, in _install_setup_requires
        dist.fetch_build_eggs(dist.setup_requires)
      File "/home/vlizana/repos/vlizanae/pyntual/.tox/py36/lib/python3.6/site-packages/setuptools/dist.py", line 702, in fetch_build_eggs
        replace_conflicting=True,
      File "/home/vlizana/repos/vlizanae/pyntual/.tox/py36/lib/python3.6/site-packages/pkg_resources/__init__.py", line 790, in resolve
        raise VersionConflict(dist, req).with_context(dependent_req)
    pkg_resources.ContextualVersionConflict: (importlib-metadata 2.0.0 (/tmp/pip-req-build-o9i6ucw5/.eggs/importlib_metadata-2.0.0-py3.6.egg), Requirement.parse('importlib-metadata<2,>=0.12'), {'tox'})
    ----------------------------------------
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

[cjw296]

@StingyJack / @vlizanae - what's worked for me is using the new pip solver: pip install --use-feature=2020-resolver ..., hope it helps!

[StingyJack]

I just stopped using floating versions. This wasn't the only patch version break that burned me.