Update serializers.py

Treat the input queryset as it comes (maybe it has been changed in a higher level). Evaluating .all() does nothing if or if not is a queryset.

rest_framework/serializers.py

@@ -517,9 +517,8 @@ class ListSerializer(BaseSerializer):
         """
         List of object instances -> List of dicts of primitive datatypes.
         """
-        iterable = data.all() if (hasattr(data, 'all')) else data
         return [
-            self.child.to_representation(item) for item in iterable
+            self.child.to_representation(item) for item in data
         ]
 
     def validate(self, attrs):