$ git clone -n https://src.fedoraproject.org/rpms/celluloid.git /var/lib/mock/f40-build-744705-111799/root/chroot_tmpdir/scmroot/celluloid
Cloning into '/var/lib/mock/f40-build-744705-111799/root/chroot_tmpdir/scmroot/celluloid'...
$ git fetch origin edc7d5d4bcbc6f23515f4a2170783155a9f1fbd5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/celluloid
 * [new ref]         edc7d5d4bcbc6f23515f4a2170783155a9f1fbd5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at edc7d5d Update to 0.26.