Please don't drop historic obsoletes:

Please don't drop historic obsoletes:

[Jon Turney]

I notice that python2-2.7.18-2 and later drop the 'obsoletes: python' 
which python2-2.7.18-1 and earlier had.

This isn't right, as there's nothing in calm which memorizes that it's 
seen that (nor should there be), so that obsoletes: doesn't effect later 
packages, and will be forgotten when the last package containing it is 
expired.

Here's a list of packages which seem to have this error (assuming the 
referenced package isn't being un-obsoleted).  I'll look at fixing these 
on sourceware, but in future, please don't do this in these or other 
packages.

> package 'idle2' version 2.7.18-4 drops 'obsoletes: idle' seen in earlier version 2.7.18-1
> package 'python2' version 2.7.18-4 drops 'obsoletes: python' seen in earlier version 2.7.18-1
> package 'python27-nghttp2' version 1.43.0-1 drops 'obsoletes: python-nghttp2' seen in earlier version 1.37.0-1
> package 'python2-bcrypt' version 3.1.7-1 drops 'obsoletes: python-bcrypt' seen in earlier version 3.1.4-1
> package 'python2-devel' version 2.7.18-4 drops 'obsoletes: python-devel' seen in earlier version 2.7.18-1
> package 'python2-gi' version 3.26.1-2 drops 'obsoletes: python-gi' seen in earlier version 3.26.1-1
> package 'python2-h5py' version 2.10.0-1 drops 'obsoletes: python-h5py' seen in earlier version 2.9.0-1
> package 'python2-ming' version 0.4.8-3 drops 'obsoletes: python-ming' seen in earlier version 0.4.8-2
> package 'python2-nghttp2' version 1.43.0-1 drops 'obsoletes: python-nghttp2' seen in earlier version 1.31.0-1
> package 'python2-zmq' version 19.0.2-1 drops 'obsoletes: python-zmq' seen in earlier version 17.0.0-1
> package 'python38-bugzilla' version 3.1.0-1 drops 'obsoletes: bugzilla-cli' seen in earlier version 3.0.2-1
> package 'python38-commonmark' version 0.9.1-2 drops 'obsoletes: commonmark' seen in earlier version 0.9.1-1
> package 'python38-pylint' version 2.12.1-1 drops 'obsoletes: pylint' seen in earlier version 2.6.0-1
> package 'python38-pypdf' version 1.27.0-2 drops 'obsoletes: python-pypdf' seen in earlier version 1.27.0-1