bug fix on TC.
bug fix on TC.

jongwook/incubator-s2graph,daewon/incubator-s2graph,jongwook/incubator-s2graph,daewon/incubator-s2graph,SteamShon/incubator-s2graph,SteamShon/incubator-s2graph,SteamShon/incubator-s2graph