$ git clone -n https://src.fedoraproject.org/rpms/f44-backgrounds.git /var/lib/mock/f45-build-8626-392/root/chroot_tmpdir/scmroot/f44-backgrounds
Cloning into '/var/lib/mock/f45-build-8626-392/root/chroot_tmpdir/scmroot/f44-backgrounds'...
$ git fetch origin ec861b560d599c2f9e2a30359972714cc6f03bc0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/f44-backgrounds
 * [new ref]         ec861b560d599c2f9e2a30359972714cc6f03bc0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ec861b5 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild