$ git clone -n https://src.fedoraproject.org/rpms/f28-backgrounds.git /var/lib/mock/f40-build-2663500-67006/root/chroot_tmpdir/scmroot/f28-backgrounds
Cloning into '/var/lib/mock/f40-build-2663500-67006/root/chroot_tmpdir/scmroot/f28-backgrounds'...
$ git fetch origin c281e1da34ee46b7a9b266371f7f212fb2dc8053:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/f28-backgrounds
 * [new ref]         c281e1da34ee46b7a9b266371f7f212fb2dc8053 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c281e1d Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild