private void firstStartSessionState() {
    String execEngine = conf.get("hive.execution.engine");
    conf.set("hive.execution.engine", "mr");
    SessionState.start(conf);
    conf.set("hive.execution.engine", execEngine);
  }
Clear out any side effects of running tests
itests/util/src/main/java/org/apache/hadoop/hive/ql/QTestUtil.java