!13199 Fix the bug of bachnorm weights are not properly loaded from the pure mindspore resnet in FasterRCNN

From: @dessyang
Reviewed-by: @robingrosman,@linqingke
Signed-off-by: @linqingke

model_zoo/official/cv/faster_rcnn/train.py

@@ -124,6 +124,25 @@ if __name__ == '__main__':
     load_path = args_opt.pre_trained
     if load_path != "":
         param_dict = load_checkpoint(load_path)
+
+        key_mapping = {'down_sample_layer.1.beta': 'bn_down_sample.beta',
+                       'down_sample_layer.1.gamma': 'bn_down_sample.gamma',
+                       'down_sample_layer.0.weight': 'conv_down_sample.weight',
+                       'down_sample_layer.1.moving_mean': 'bn_down_sample.moving_mean',
+                       'down_sample_layer.1.moving_variance': 'bn_down_sample.moving_variance',
+                       }
+        for oldkey in list(param_dict.keys()):
+            if not oldkey.startswith(('backbone', 'end_point', 'global_step', 'learning_rate', 'moments', 'momentum')):
+                data = param_dict.pop(oldkey)
+                newkey = 'backbone.' + oldkey
+                param_dict[newkey] = data
+                oldkey = newkey
+            for k, v in key_mapping.items():
+                if k in oldkey:
+                    newkey = oldkey.replace(k, v)
+                    param_dict[newkey] = param_dict.pop(oldkey)
+                    break
+
         for item in list(param_dict.keys()):
             if not item.startswith('backbone'):
                 param_dict.pop(item)