[Python-Dev] Support the /usr/bin/python2 symlink upstream

["Martin v. Löwis"]

> Here is a draft PEP (forgive me if it's incorrectly formatted; I've
> never done this before).

LGTM. Please specify what /usr/bin/python is supposed to be also
(rather: the "python" utility). I'd like it ruled out that
installations *only* provide python2 and python3 - "python" could
be either one, but should be present "normally" (i.e. SHOULD
in the RFC 2119 sense).

Nitpickingly, I'd add that scripts can, of course, also specify
python2.7 (or some such). Actually, scripts can do whatever they
want - it's more about what they then can expect to happen.

Regards,
Martin