$ git clone -n https://src.fedoraproject.org/rpms/rabbitsign.git /var/lib/mock/f45-build-34271-683/root/chroot_tmpdir/scmroot/rabbitsign
Cloning into '/var/lib/mock/f45-build-34271-683/root/chroot_tmpdir/scmroot/rabbitsign'...
$ git fetch origin b3011b59ea8c75328f7a7bab5a6e11b63d24f3af:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rabbitsign
 * [new ref]         b3011b59ea8c75328f7a7bab5a6e11b63d24f3af -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b3011b5 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild