$ git clone -n https://src.fedoraproject.org/rpms/f40-backgrounds.git /var/lib/mock/f45-build-8681-393/root/chroot_tmpdir/scmroot/f40-backgrounds
Cloning into '/var/lib/mock/f45-build-8681-393/root/chroot_tmpdir/scmroot/f40-backgrounds'...
$ git fetch origin ad295052ea2fd3f990108657999c3b3a9611bbc5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/f40-backgrounds
 * [new ref]         ad295052ea2fd3f990108657999c3b3a9611bbc5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ad29505 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild