Buildout relies on setuptools to fetch dists from package indexes like
PyPI. Setuptools infers the project name of source distributions found
in the index from their filename, as derived from their download link.

This works on the assumption the sdist filename corresponds losslessly
to the project name, and in the way setuptools expects.

Setuptools normalizes any occurrence of a non alphanumeric and non '.'
character into a '-'. This is actually already lossy for project names
that contain other characters; therefore the assumption should instead
be that the sdist filename is lossless with regards to this normalized
project name - in general project names should respect this normalized
form.

Since PEP 625, that assumption is definitely broken, i.e. the filename
is lossy with regards to the normalized project name:
- in the sdist filename, characters . and - must both be replaced by _
- in the sdist filename, all characters must be lowercased

Internally, setuptools lowercases the normalized project name in order
to compare dists. The possibles consequences of that broken assumption
are thus:
1. the sdist is discarded from the search
2. the sdist is found but the project name may be cased differently

For example, zc.buildout==3.0.1 yields zc_buildout-3.0.1.tar.gz, which
results in setuptools interpreting the project name as zc-buildout and
discarding it from the search.

Workaround 1. by also looking up the name with . replaced by _.
Workaround 2. by fixing the project names back to the looked-up name.