set origin= for distutils.__spec__

[asottile]

set origin so spec finding reports the correct location -- https://docs.python.org/3/library/importlib.html#importlib.machinery.ModuleSpec

Summary of changes

Closes asottile/reorder-python-imports#210

Pull Request Checklist

• Changes have tests
• News fragment added in changelog.d/.
  (See documentation for details)

[jaraco]

Inferring from the bug report, the issue is that the DistutilsMetaFinder is creating a spec without a valid origin, creating a spec that is inferred to be a namespace package.

I might re-arrange the test a bit, but this is great. Thanks for the contrib.

[jaraco]

I confirmed that 91ce77e captures the failed expectation when run with SETUPTOOLS_USE_DISTUTILS=local, which is run in CI, so I believe it to be a more selective and less entangled test.