With the introduction of `pip_args` option, you can easily extend the
`:pip` installation mode behaviour. But some interesting/advanced usages
are still not possible because of the auto-generated parts ("ansible"
package, version selection, and the `--upgrade` flag).
By adding this "pip_args_only" install mode, it will be for instance
possible to:
- install unofficial releases, like release candidates published at
https://releases.ansible.com/
- install more pip packages (e.g. via a `requirements.txt` file), with
hash validation, etc.
Note that there is no config validation that requires `pip_args` option
to be defined when the :pip_args_only mode is selected. This would be
more elegant, and user friendly to raise a configuration error, but this
can wait. At least, running with an empty `pip_args` won't lead to any
command crash, since the rather dummy "pip install" shows an helper
notice and terminates with a zero (0) exit code.
This change is thought as a complement to the changes originally
proposed in pull request GH-8170.
80d105cf8c