Change to only BaseManager

Author: 954-Ivory

rest_framework/serializers.py

@@ -681,9 +681,7 @@ def to_representation(self, data):
         """
         # Dealing with nested relationships, data can be a Manager,
         # so, first get a queryset from the Manager if needed
-        iterable = data.all() if isinstance(data, (
-            models.manager.Manager, models.manager.BaseManager
-        )) else data
+        iterable = data.all() if isinstance(data, models.manager.BaseManager) else data
 
         return [
             self.child.to_representation(item) for item in iterable