Package-split upgrade path

[Rex Dieter]

Sandro Mani wrote:

> Hello,
> 
> In python-pillow (the python imaging fork which replaced PIL in F19+),
> there is a module (ImageQt) which requires PyQt4, but that dependency is
> missing in python-pillow (and in python-imaging before). I don't really
> like adding PyQt4 as a dependency to the main package, since it pulls in
> lots of stuff. So, I'd go for creating a python-pillow-qt subpackage
> (albeit with just one file), and now am wondering about the upgrade
> path. From what I can see, there is just one package which uses the
> ImageQt module (pony, which actually looks to be rather unmaintained).
> Question: What is the best way to proceed?

make python-pillow-qt include

Obsoletes: python-pillow <  #last_EVR_before_qt_subpkg_existed#
Requires: python-pillow = %{version}-%{release}