$ git clone -n https://src.fedoraproject.org/rpms/rubygem-clutter.git /var/lib/mock/f42-build-side-115087-61059189-6588325/root/chroot_tmpdir/scmroot/rubygem-clutter
Cloning into '/var/lib/mock/f42-build-side-115087-61059189-6588325/root/chroot_tmpdir/scmroot/rubygem-clutter'...
$ git fetch origin 135ef7ef28fd7e94f5c07fe07262d6387781a303:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-clutter
 * [new ref]         135ef7ef28fd7e94f5c07fe07262d6387781a303 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 135ef7e 4.3.0 entry