$ git clone -n https://src.fedoraproject.org/rpms/mfem.git /var/lib/mock/f40-build-1222542-22759/root/chroot_tmpdir/scmroot/mfem
Cloning into '/var/lib/mock/f40-build-1222542-22759/root/chroot_tmpdir/scmroot/mfem'...
$ git fetch origin 2973c05e222b306661d1b560b480db970a866e1e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mfem
 * [new ref]         2973c05e222b306661d1b560b480db970a866e1e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2973c05 4.7