Ensure that ORDER BY clauses from default scopes are not included in...

Ensure that ORDER BY clauses from default scopes are not included in calculation queries. Fixes #406.

activerecord/lib/active_record/relation/calculations.rb

@@ -197,7 +197,7 @@ def operation_over_aggregate_column(column, operation, distinct)
 
     def execute_simple_calculation(operation, column_name, distinct) #:nodoc:
       # Postgresql doesn't like ORDER BY when there are no GROUP BY
-      relation = except(:order)
+      relation = reorder(nil)
 
       if operation == "count" && (relation.limit_value || relation.offset_value)
         # Shortcut when limit is zero.

activerecord/test/cases/relation_scoping_test.rb

@@ -462,4 +462,8 @@ def test_unscoped_with_named_scope_should_not_have_default_scope
     assert DeveloperCalledJamis.unscoped.poor.include?(developers(:david).becomes(DeveloperCalledJamis))
     assert_equal 10, DeveloperCalledJamis.unscoped.poor.length
   end
+
+  def test_default_scope_order_ignored_by_aggregations
+    assert_equal DeveloperOrderedBySalary.all.count, DeveloperOrderedBySalary.count
+  end
 end