Suggest documenting that `packages_distributions` won't work with editable installs

[layday]

As discussed in pypa/packaging-problems#609, PEP 660 editable wheels which are generated by backends other than setuptools will not contain a top_level.txt and with the RECORD only listing e.g. the pth file with an entry to the original package directory, packages_distributions will not be able to reconcile editable packages with their corresponding distributions.

[pfmoore]

A longer term alternative to simply documenting the limitation would be to standardise something equivalent to top_level.txt.

[Helveg]

Is there a planned solution for this being tracked anywhere?

[jaraco]

I'm not aware of one. It would require expanding the standard for editable installs to provide the necessary metadata. There's nothing importlib_metadata can do until that happens. It looks like pypa/packaging-problems#620 already tracks a similar if not identical concern. Feel free to chime in and contribute there.