Description of problem:
So I lost rpm building functionality. rpm -b fails with a really unclear
instead of somehow saying that components are missing.
An strace lead to /usr/lib/rpm/rpmb which i didn't have. an rpm -qf of that
a freshly installed 7.1 located my missing package.
Yes, the build modes of rpm have been broken off a different executable.
You need to install the rpm-build package.