If you attempt to build an rpm without having first installed the rpm-build package, rpm simply returns a list of RPM command options. It should report that rpm-build capability is not installed. Better yet, it should not list the rpm build options in the option list, and have a notation that rpm-build is not installed.
Additionally, during an Upgrade, it (the RPM in the second stage image) will not --rebuilddb as packaged in beta-2. This prevents credible attempts to fix a hosed partially upgraded RPM database.
rpm is being split into possibly 5 executables, and the build modes have already been moved to a new executable /usr/bin/rpmb. Meanwhile, to cope with the transition, rpm rexecutes /usr/bin/rpmb [passing the original arguments, and there is no way using current popt aliases to identify the failed exec when rpm-build is not installed. I'd suggest that you should start to type rpmb when building, and be prepared for the executable to be renamed to (IMHO sligltly less nerdy, YMMV) rpmbuild. The other issue with --rebuilddb is a whole different can of worms. Please add a new bug with more details if you wish me to fix.