fix checkpoint evaliaction.

mindspore/train/serialization.py

@@ -187,6 +187,7 @@ def load_checkpoint(ckpt_file_name, model_type="normal", net=None):
         raise ValueError(e.__str__())
 
     parameter_dict = {}
+    if checkpoint_list.model_type:
         if model_type != checkpoint_list.model_type:
             raise KeyError("Checkpoint file model type({}) is not equal to input model type({}).".format(
                 checkpoint_list.model_type, model_type))