Increase multi option performance by not doing a query if its already prefetched.

Author: Joey Jurjens

oscar_odin/mappings/catalogue.py

@@ -207,7 +207,7 @@ def _attribute_value_to_native_type(item):
                 return item.value.option
 
             elif obj_type == item.attribute.MULTI_OPTION:
-                return item.value.values_list("option", flat=True)
+                return [value.option for value in item.value]
 
             elif obj_type == item.attribute.FILE:
                 return item.value.url