Versioneer causes `fatal: bad revision 'HEAD'` under special circumstances

The full story is available in https://github.com/datalad/datalad-osf/pull/100 and a tentative fix was proposed at https://github.com/datalad/datalad-osf/pull/100#issuecomment-650316993 by @kyleam

The summary is:

• Deploying a Python package in editable fashion (pip install -e .) that installs a Git remote helper leads to unconditional fatal: bad revision 'HEAD' messages in boilerplate code.
• ultimately this is due to an inadequate execution environment that versioneer is using to run Git commands
• a minimal demo is contained in https://github.com/datalad/datalad-osf/pull/100#issuecomment-650316993

[effigies]

It looks like a bad cmdclass here.

>>> import versioneer
>>> versioneer.get_cmdclass()
{'version': versioneer.get_cmdclass.<locals>.cmd_version,
 'build_py': versioneer.get_cmdclass.<locals>.cmd_build_py,
 'sdist': versioneer.get_cmdclass.<locals>.cmd_sdist}

What you probably want is something like:

cmdclass = versioneer.get_cmdclass()
cmdclass['build_ext'] = HelicsBuild

...
setup(
    ...
    cmdclass=cmdclass,
    ...
)

You should be able to see whether it’s working with something like:

$ python setup.py version 
running version
keywords are unexpanded, not using
got version from VCS {'version': '3.1.1+108.g7ce84f3e', 'full-revisionid': '7ce84f3e357dd39d280def45ce6b29c7f195e715', 'dirty': False, 'error': None, 'date': '2020-09-20T09:41:23-0400'}
Version: 3.1.1+108.g7ce84f3e
 full-revisionid: 7ce84f3e357dd39d280def45ce6b29c7f195e715
 dirty: False
 date: 2020-09-20T09:41:23-0400

[nightlark]

Ahh, thanks! That actually helps a lot with understanding how cmdclass works.