Minor fix

coin/configuration/admin.py

@@ -15,7 +15,6 @@ class ParentConfigurationAdmin(PolymorphicParentModelAdmin):
     base_model = Configuration
     polymorphic_list = True
     list_display = ('model_name','configuration_type_name', 'offersubscription', 'offer_subscription_member')
-    search_fields = ['polymorphic_ctype']
 
     def offer_subscription_member(self, config):
         return config.offersubscription.member