code: private void failReduceUnprotected(TaskInProgress tip) {
      if (nonRunningReduces == null) {
        LOG.warn("Failed cache for reducers missing!! "
                 + "Job details are missing.");
        return;
      }
      nonRunningReduces.add(0, tip);
    }
docs: Adds a failed TIP in the front of the list for non-running reduces
  @param tip the tip that needs to be failed