使用最新的PaddleDetection，run 了yolov4的模型报错，

环境aistudio GPU环境，python3.6，paddle1.7.1， 1.8都试了有问题，问题如下

Traceback (most recent call last):
File "tools/train.py", line 366, in
main()
File "tools/train.py", line 113, in main
train_fetches = model.train(feed_vars)
File "/home/aistudio/PaddleDetection/ppdet/modeling/architectures/yolo.py", line 156, in train
return self.build(feed_vars, mode='train')
File "/home/aistudio/PaddleDetection/ppdet/modeling/architectures/yolo.py", line 85, in build
gt_score, targets)
File "/home/aistudio/PaddleDetection/ppdet/modeling/anchor_heads/yolo_head.py", line 294, in get_loss
self.prefix_name)
File "/home/aistudio/PaddleDetection/ppdet/modeling/losses/yolo_loss.py", line 69, in call
mask_anchors, self._ignore_thresh)
File "/home/aistudio/PaddleDetection/ppdet/modeling/losses/yolo_loss.py", line 169, in _get_fine_grained_loss
num_classes, downsample, self._ignore_thresh, scale_x_y)
File "/home/aistudio/PaddleDetection/ppdet/modeling/losses/yolo_loss.py", line 294, in _calc_obj_loss
scale_x_y=scale_x_y)
TypeError: yolo_box() got an unexpected keyword argument 'scale_x_y'