macros.python2 requires update in F21+

[Haïkel]

Hi,

Recently, we had a lot of issues with openstack packages due to python
newer guidelines.
To fix upgrade path for python2 modules, you had to obsolete previous
python-xxx module.
Orion committed a fix in rawhide in the macro %python_provides that
fixes that issue.

http://pkgs.fedoraproject.org/cgit/python.git/commit/?id=7fdb9bedcda48894b7ba85e34ca5722b28b69076
http://pkgs.fedoraproject.org/cgit/python.git/commit/?id=cb9dd734593c52b84f0b9b6f19f352001c1d50d3

Could we backport these in F21/22/23 ?
It's rather critical, as we have less experienced packagers pushing
updates without checking
the upgrade path or provides/obsoletes. Having a reliable
%python_macros as in rawhide makes it more
robust and will avoid breaking users dependencies

I prefer that python maintainers do the update as it's a critical
package, but I don't mind doing it in their stead
if you approve this (if necessary)


Regards,
H.