[Dygraph] solve load optimizer if some key not in optimizer (#1812)

* solve load optimizer if some key not in optimizer

* variable name tmp_key to key

* add comment

ppdet/utils/checkpoint.py

@@ -92,6 +92,10 @@ def load_weight(model, weight, optimizer=None):
 
     if optimizer is not None and os.path.exists(path + '.pdopt'):
         optim_state_dict = paddle.load(path + '.pdopt')
+        # to slove resume bug, will it be fixed in paddle 2.0
+        for key in optimizer.state_dict().keys():
+            if not key in optim_state_dict.keys():
+                optim_state_dict[key] = optimizer.state_dict()[key]
         optimizer.set_state_dict(optim_state_dict)
     return