Processing ./wheelhouse/python-dateutil-2.7.0.tar.gz fails in charm software installation

[jamesbeedy]

Hitting this https://paste.ubuntu.com/p/Jc7DTKSjbg/ on all charms that pull in python-dateutil as a dependency of something in wheelhouse.txt.

[johnsca]

For the record (since this bug is referenced in the code comment), this is apparently due to pip not picking up on dependencies that are listed in setup_requires rather than install_requires to add them to the wheelhouse, and may well be resolved in pip 10 when that becomes available. Technically, this could affect packages other than setuptools, but that definitely seems like it would be the most common case where this would be encountered by far.

Ref:

• "setuptools_scm" could not be found pypi/legacy#322 (comment)
• Avoid using setup_requires parameter in setup.py. pytest-dev/pytest-xdist#136
• https://www.python.org/dev/peps/pep-0518/