Avoid erroneous version warning for .dist-info

[charliermarsh]

Summary

Since #7208, this is now always firing, for every directory, because the version gets normalized (e.g., 1.2.3 gets normalized to 1-2-3, which never matches the parsed version). pip doesn't warn here, I guess we won't either, because I can't figure out a robust way to do this... We need to get the non-normalized remainder after stripping the normalized package name, but we strip the normalized package name from the normalized string, so we only have a normalized remainder.