Merge pull request #107 from Lornatang/fix-reference-bugs

fix refrence bug

train.py

@@ -4,6 +4,7 @@ import torch.distributed as dist
 import torch.nn.functional as F
 import torch.optim as optim
 import torch.optim.lr_scheduler as lr_scheduler
+import torch.utils.data
 from torch.utils.tensorboard import SummaryWriter
 
 import test  # import test.py to get mAP after each epoch