$ git clone -n https://src.fedoraproject.org/rpms/lovelock-backgrounds.git /var/lib/mock/f45-build-17556-501/root/chroot_tmpdir/scmroot/lovelock-backgrounds
Cloning into '/var/lib/mock/f45-build-17556-501/root/chroot_tmpdir/scmroot/lovelock-backgrounds'...
$ git fetch origin 287b9f8df17741ea381db6ce92bfaea90f0f9d3a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/lovelock-backgrounds
 * [new ref]         287b9f8df17741ea381db6ce92bfaea90f0f9d3a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 287b9f8 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild