bug#45655: Please use 'python3' command instead of 'python'

[Stefan Monnier <monnier@iro.umontreal.ca>]

> I don't think keeping `python` is a good idea, this would make Emacs
> considered to be buggy in Debian.
>
> Please see https://wiki.debian.org/Python :
> ...
> NOTE: Debian testing (bullseye) has removed the "python" package and
> the '/usr/bin/python' symlink due to the deprecation of Python 2. No
> packaged scripts should depend on the existence of '/usr/bin/python':
> if they do, that is a bug that should be reported to Debian. You can
> use the 'python-is-python3' or 'python-is-python2' packages to restore
> an appropriate '/usr/bin/python' symlink for third-party or legacy
> scripts.
> ...

That's a very different situation, tho: what you describe is for Debian
packages, where clearly each package is written&tested to work against
a particular version (or range of versions) of Python.

In contrast the question at hand is "which version of Python should one
start when the user wants to run a Python subprocess".  I think it's
reasonable to consider that *if* there is a `python` executable in
$PATH, it makes sense to considered it as the preferred version
of Python.


        Stefan