$ git clone -n https://src.fedoraproject.org/rpms/f33-backgrounds.git /var/lib/mock/f45-build-8599-391/root/chroot_tmpdir/scmroot/f33-backgrounds
Cloning into '/var/lib/mock/f45-build-8599-391/root/chroot_tmpdir/scmroot/f33-backgrounds'...
$ git fetch origin b713e74b09260934f478578438c1e3d26b02fa03:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/f33-backgrounds
 * [new ref]         b713e74b09260934f478578438c1e3d26b02fa03 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b713e74 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild