$ git clone -n https://src.fedoraproject.org/rpms/f29-backgrounds.git /var/lib/mock/f40-build-2292028-56094/root/chroot_tmpdir/scmroot/f29-backgrounds
Cloning into '/var/lib/mock/f40-build-2292028-56094/root/chroot_tmpdir/scmroot/f29-backgrounds'...
$ git fetch origin adbf96df6e99867bed8a45d7df20257011f07e4c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/f29-backgrounds
 * [new ref]         adbf96df6e99867bed8a45d7df20257011f07e4c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at adbf96d Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild