$ git clone -n https://src.fedoraproject.org/rpms/Cython.git /var/lib/mock/f40-build-2209741-52168/root/chroot_tmpdir/scmroot/Cython
Cloning into '/var/lib/mock/f40-build-2209741-52168/root/chroot_tmpdir/scmroot/Cython'...
$ git fetch origin 4f6fdd4aa88515e1a6848ae1cb22aa75c1ac31fd:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/Cython
 * [new ref]         4f6fdd4aa88515e1a6848ae1cb22aa75c1ac31fd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4f6fdd4 Update to 3.0.6