Need a proper release (not a pre-release)

[paugier]

For one project, I use tox-pipenv and one package (fluidpythran) depends on Black.

Pipenv complains loudly of the fact that there is only pre-release of Black and fails because of that. Since I used pipenv through tox, I can't add the --pre option. Anyway, it would be better not to have it...

A simple solution to this problem would be to have a proper release of Black, with a version without "a" or "b"...

Pipenv's complain:

Warning: Your dependencies could not be resolved. You likely have a mismatch in your sub-dependencies.
  You can use $ pipenv install --skip-lock to bypass this mechanism, then run $ pipenv graph to inspect the situation.
  Hint: try $ pipenv lock --pre if it is a pre-release dependency.
Could not find a version that matches black (from -r /tmp/pipenv-c310e9_t-requirements/pipenv-cysm1vet-constraints.txt (line 4))
Skipped pre-versions: 18.3a0, 18.3a0, 18.3a1, 18.3a1, 18.3a2, 18.3a2, 18.3a3, 18.3a3, 18.3a4, 18.3a4, 18.4a0, 18.4a0, 18.4a1, 18.4a1, 18.4a2, 18.4a2, 18.4a3, 18.4a3, 18.4a4, 18.4a4, 18.5b0, 18.5b0, 18.5b1, 18.5b1, 18.6b0, 18.6b0, 18.6b1, 18.6b1, 18.6b2, 18.6b2, 18.6b3, 18.6b3, 18.6b4, 18.6b4, 18.9b0, 18.9b0
There are incompatible versions in the resolved dependencies.

[paugier]

Duplicate of #517

Sorry for the noise. I'm going to avoid black dependency for now.