I sent this to
https://lists.fedoraproject.org/pipermail/rel-eng/2015-March/019507.html
as well, but I think it's also a useful topic here. I started this wiki page:
https://fedoraproject.org/wiki/Layered_build_scripts_for_package_maintainers
And I added a new project I've been working on there:
https://github.com/cgwalters/rpmdistro-gitoverlay
Like most of the other scripts, there, it's a hack, but for people who
want something more like "automated git COPR", hopefully it'll
be useful.
And if you know of other projects in this area, please add them!