$ git clone -n https://src.fedoraproject.org/rpms/python-tornado.git /var/lib/mock/f40-build-2168588-50976/root/chroot_tmpdir/scmroot/python-tornado
Cloning into '/var/lib/mock/f40-build-2168588-50976/root/chroot_tmpdir/scmroot/python-tornado'...
$ git fetch origin f68b1fcc047a8c184623ddd8fd790ca96bd5812b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/python-tornado
 * [new ref]         f68b1fcc047a8c184623ddd8fd790ca96bd5812b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f68b1fc 6.3.3