When building source distributions, we need to include the readme, so it
can become part the METADATA body when building the wheel. We also need
to support the license files from PEP 639. When building the source
distribution, we copy those file relative to their origin, when building
the wheel, we copy them to `.dist-info/licenses`.
The test for idempotence in wheel building is merged into the file
listing test, which also covers that source tree -> source dist -> wheel
is equivalent to source tree -> wheel, though we do need to check for
file inclusion stronger here.
Best reviewed commit-by-commit
A first milestone: source tree -> source dist -> wheel -> install works.
This PR adds a test for this.
There's obviously a lot still missing, including basics such as the
Readme inclusion.
konsti