$ git clone -n https://src.fedoraproject.org/rpms/rubygem-ruby-rc4.git /var/lib/mock/f45-build-35222-694/root/chroot_tmpdir/scmroot/rubygem-ruby-rc4
Cloning into '/var/lib/mock/f45-build-35222-694/root/chroot_tmpdir/scmroot/rubygem-ruby-rc4'...
$ git fetch origin b51ecec7ff88015916ec4ff628d1bfb8e5cebaa6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-ruby-rc4
 * [new ref]         b51ecec7ff88015916ec4ff628d1bfb8e5cebaa6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b51ecec Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild