Summary of coco installation issues on April 27th, 2021 hotfix

[anjakefala]

When installing coco manually or through ansible, this message was encountered:

  WARNING: Built wheel for coco is invalid: Metadata 1.2 mandates PEP 440 version, but '2021.04-hotfix' is not
Failed to build coco
Installing collected packages: coco
  Attempting uninstall: coco
    Found existing installation: coco 2021.04-hotfix
    Uninstalling coco-2021.04-hotfix:
      Successfully uninstalled coco-2021.04-hotfix
    Running setup.py install for coco ... done
  DEPRECATION: coco was installed using the legacy 'setup.py install' method, because a wheel could not be built for it. A possible replacement is to fix the wheel build issue reported above. You can find discussion regarding this at https://github.com/pypa/pip/issues/8368.
Successfully installed coco-2021.04-hotfix
WARNING: You are using pip version 21.0.1; however, version 21.1 is available.
You should consider upgrading via the '/bin/python3 -m pip install --upgrade pip' command.

coco would "install", but it would fail to start from the commandline because of "bad interpreter" issues.

[andre@cndhn ~]$ coco reset-state
-bash: /usr/local/bin/coco: python: bad interpreter: No such file or directory

[rick@cndhn ~]$ python3
Python 3.7.4 (default, Apr  6 2020, 16:27:34) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import coco
>>> coco.__version__
'2021.04-hotfix'

The shebang for scripts/coco was being modified

I think it's about the first line in carillon:/usr/local/bin/coco:
#!python

Setuptools modifies shebangs so that the environment python is used.

This conversation implies that #!python is an intermediate shebang, that is supposed to be expanded when the wheel is built.

The current hypothesis is that the newer pip started becoming finicky about versions adhering to PEP 440, and failed to build the wheel. It did not like the version '2021.04-hotfix'. This resulted in #!python not being expanded, and coco being installed with this un-expanded shebang.

Some more info: https://www.python.org/dev/peps/pep-0427/#recommended-installer-features
7f9c009