$ git clone -n https://src.fedoraproject.org/rpms/f34-backgrounds.git /var/lib/mock/f40-build-2261384-54434/root/chroot_tmpdir/scmroot/f34-backgrounds
Cloning into '/var/lib/mock/f40-build-2261384-54434/root/chroot_tmpdir/scmroot/f34-backgrounds'...
$ git fetch origin dacc6798aa13c8030fc670042950e3d385ba73e4:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/f34-backgrounds
 * [new ref]         dacc6798aa13c8030fc670042950e3d385ba73e4 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dacc679 Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild