$ git clone -n https://src.fedoraproject.org/rpms/f32-backgrounds.git /var/lib/mock/f45-build-8595-391/root/chroot_tmpdir/scmroot/f32-backgrounds
Cloning into '/var/lib/mock/f45-build-8595-391/root/chroot_tmpdir/scmroot/f32-backgrounds'...
$ git fetch origin 6cba843c07a116904dfc33d52bcf51d17d26633f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/f32-backgrounds
 * [new ref]         6cba843c07a116904dfc33d52bcf51d17d26633f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6cba843 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild