Since PEP 625, sdist filenames replace . and - in the project name by
_, such as e.g. zc.buildout==3.0.1 yielding zc_buildout-3.0.1.tar.gz.

However, when looking up available dists in a package index, when an
sdist with such a normalized filename is found, setuptools interprets
the filename by replacing _ with - and uses that as the dist's name;
e.g. zc_buildout-3.0.1.tar.gz yields zc-buildout. This causes lookups
for the name with . (e.g.: zc.buildout) to fail.

Workaround by also looking up the name with . replaced by _, and then
fixing the names of found dists back to expected name.