Fallback to a placeholder if a distribution's location is None

[daniil-konovalenko]

Resolves #11704

I would love to hear some thoughts on the message wording. I feel it's not very friendly right now because it doesn't specify how pip found the package. Should we log the finder class that found the package, maybe? Not sure if it's possible though without changing the importlib API.

[uranusjr]

If I remember correctly, this is shown to the user, so including the finder class doesn’t feel like a good idea. Where would you need that information?

[daniil-konovalenko]

If I remember correctly, this is shown to the user, so including the finder class doesn’t feel like a good idea. Where would you need that information?

Right, it's not the best thing to show to the user. It's just from the user point of view the current message doesn't explain much.
I don't see a better way at the moment, so I guess we could just merge it and be done with it, and maybe return to it in the future if needed.