ValueError: too many values to unpack (expected 3)

Hi, thanks for your work.
I implemented base training myself, and then fine-tune.
I have run bash run/test_voc_first.sh and got this error randomly.
ValueError: too many values to unpack (expected 3)
The error happens in imdb.evaluate_detections(all_boxes, output_dir, **vars(args)).
How to solve it ?
Thanks!