pass the correct reflection to HasManyThroughAssociationPolymorphicError

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@4106 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/lib/active_record/reflection.rb

@@ -174,7 +174,7 @@ def check_validity!
           end
           
           if source_reflection.options[:polymorphic]
-            raise HasManyThroughAssociationPolymorphicError.new(class_name, @reflection, source_reflection)
+            raise HasManyThroughAssociationPolymorphicError.new(class_name, self, source_reflection)
           end
         end
       end