To make rpmbuild work properly, a tar ball has to be generated explicitly first.
Not really. You just have to be aware of the constraints imposed by rpm, which is that the %_builddir is deleted at the start of %build. Other than that there is little in the way of things. No Source: lines are needed in the .spec.
%build mv %_sourcedir/* ./ %configure %make_build
works, provided you somehow populated rpmbuild/SOURCES/ somehow (which is not a big deal when calling rpmbuild itself, but can be when extra layers like OBS are on top - but that's not rpmbuild's fault).
Thanks for that hint, that worked out finally. My misunderstanding was the %prep step, which, when left out completely, does not complain about anything missing any longer. And, as you said, the %_sourcedir has to be populated – my approach is to call rpmbuild as follows in the git working directory: rpmbuild --define "_sourcedir $(pwd)" -ba *.spec This overhead is fairly tolerable. Cheers, Florian