@0arthur, thanks for your PR! By analyzing the history of the files in this pull request, we identified @FRidh to be a potential reviewer.

The packages is broken as it stands.

What is broken?

This is still a problem - comment out the propagatedBuildInputs line and you will see test failures.

Just rebased off master and updated from 15.5.5 to 15.5.6.

How do you work with this package?

Using this as a build input without also specifying git or mercurial.

Alright, then it indeed makes sense. Note that with the current infra we cannot add mercurial as propagatedBuildInput because it will mess up PYTHONPATH.

Sorry, don't bother, I see the problem now I think about it.

The issue is that mercurial is implemented in Python. We still need to properly isolate Python applications like mercurial.

Thinking again, the propagatedBuildInputs get put on PYTHONPATH, but setuptools_scm should only ever be referenced in buildInputs, so this won't be an issue I think?

I've just reviewed usage of setuptools_scm and fixed the instances where it is referenced in propagatedBuildInputs.

Before I rebase again, are you happy in principle to merge this?

84c6e6b is in, but it doesn't include the extra dependencies.

Adding git as propagatedBuildInput is fine, but adding mercurial is not due to the mentioned isolation.
Although, a good solution that will work is replacing in the following file calls to git with the full path, and the same in for mercurial in https://github.com/pypa/setuptools_scm/blob/v1.15.6/setuptools_scm/hg.py.

If you want to pursue this I suggest you ask @RonnyPfannschmidt if he is willing to introduce GIT = 'git' and HG = 'hg' so that we only need to replace those two lines with full paths.

as far as i understood its only needed for the builds from scm repos its not needed to propagate
its not quite clear why build only requitrements need to propagate, just add them to PATH in the build