builder.py will now remove any rpms from the repository that have the same name as a scratch rpm

When the --scratch flag is passed to the builder.py script, it gets the full RPM build for the repository, and then puts any scratch build RPMs in as well. This causes a problem when the full RPM build is a newer version than the scratch build (if, for example, the latest full build is for 2.4.1 and the scratch build was for 2.4.0).

This addition just removes any RPMs that have the same name as one of the scratch build RPMs.