contrib/BS-pkg-testing/build-rpms: fix bug in backing up of _servicedata
contrib/BS-pkg-testing/build-rpms: shorten output
contrib/BS-pkg-testing/build-rpms: extract new backup_service_files() function
contrib/BS-pkg-testing/build-rpms: extract new restore_service_files() function
contrib/BS-pkg-testing/build-rpms: extract new run_source_services() function
contrib/BS-pkg-testing/build-rpms: die if can't find source service to tweak
contrib/BS-pkg-testing/build-rpms: split source service execution into run-source-services