The CVSROOT should end with /cvs/pkgs/ not /cvs/extras/ in the fedora-cvs.py script.
maybe it would be an idea to run rpmdev-setup tree if ~/rpmbuild don't exist in the fedora-packager-setup to create it.
we cant force rpmdev-setup to be run. i personally use ~/fedora as my _topdir not ~/rpmbuild. I will fix the url.
This was fixed back in r13 and is in the current packaged release.