$ git clone -n https://src.fedoraproject.org/rpms/f27-backgrounds.git /var/lib/mock/f40-build-2663496-67006/root/chroot_tmpdir/scmroot/f27-backgrounds
Cloning into '/var/lib/mock/f40-build-2663496-67006/root/chroot_tmpdir/scmroot/f27-backgrounds'...
$ git fetch origin b4e216382977e7d7222c253b32e14e6c7bdf4b42:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/f27-backgrounds
 * [new ref]         b4e216382977e7d7222c253b32e14e6c7bdf4b42 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b4e2163 Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild