text: Title: The problem of evaluation
  Body: 我在运行test.py没有什么问题，但是在跑评估运行到eval success的时候报错了:
  multiprocessing.pool.RemoteTraceback: 
  """
  Traceback (most recent call last):
    File "E:\Anaconda3\envs\pysot\lib\multiprocessing\pool.py", line 121, in worker
      result = (True, func(*args, **kwds))
    File "E:\pysot\toolkit\evaluation\ope_benchmark.py", line 50, in eval_success
      success_ret_[video.name] = success_overlap(gt_traj, tracker_traj, n_frame)
    File "E:\pysot\toolkit\utils\statistics.py", line 105, in success_overlap
      iou[mask] = overlap_ratio(gt_bb[mask], result_bb[mask])
  IndexError: too many indices for array
  """
  
  The above exception was the direct cause of the following exception:
  
  Traceback (most recent call last):
    File "E:/pysot/tools/eval.py", line 146, in <module>
      main()
    File "E:/pysot/tools/eval.py", line 52, in main
      trackers), desc='eval success', total=len(trackers), ncols=100):
    File "E:\Anaconda3\envs\pysot\lib\site-packages\tqdm\std.py", line 1107, in __iter__
      for obj in iterable:
    File "E:\Anaconda3\envs\pysot\lib\multiprocessing\pool.py", line 748, in next
      raise value
  IndexError: too many indices for array
  
  请问这是pytorch的版本问题嘛？我的pytorch版本是0.4.1 ，cuda8