$ git clone -n https://src.fedoraproject.org/rpms/f34-backgrounds.git /var/lib/mock/f45-build-8601-391/root/chroot_tmpdir/scmroot/f34-backgrounds
Cloning into '/var/lib/mock/f45-build-8601-391/root/chroot_tmpdir/scmroot/f34-backgrounds'...
$ git fetch origin 603aa7421de22569364aea36b69361ec7d3646fc:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/f34-backgrounds
 * [new ref]         603aa7421de22569364aea36b69361ec7d3646fc -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 603aa74 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild