message: TPUEstimator: Fix the outfeed thread join.
diff: @@ -283,7 +283,7 @@ class TPUInfeedOutfeedSessionHook(session_run_hook.SessionRunHook):
  if self._dequeue_ops is not None:
  logging.info('Stop output thread controller')
  - self._infeed_thd_controller.join()
  + self._outfeed_thd_controller.join()
  logging.info('Shutdown TPU system.')
  session.run(self._finalize_op)
  