$ git clone -n https://src.fedoraproject.org/rpms/f30-backgrounds.git /var/lib/mock/f40-build-2686952-68077/root/chroot_tmpdir/scmroot/f30-backgrounds
Cloning into '/var/lib/mock/f40-build-2686952-68077/root/chroot_tmpdir/scmroot/f30-backgrounds'...
$ git fetch origin 9b5d689349a8e8375857918d45d861bb26d47657:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/f30-backgrounds
 * [new ref]         9b5d689349a8e8375857918d45d861bb26d47657 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9b5d689 Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild