=== modified file 'includes/ajax.inc'
--- includes/ajax.inc	2010-09-13 01:09:25 +0000
+++ includes/ajax.inc	2010-09-17 20:21:04 +0000
@@ -242,6 +242,7 @@
   // When a form is rebuilt after AJAX processing, its #build_id and #action
   // should not change.
   // @see drupal_rebuild_form()
+  $form_state['rebuild'] = TRUE;
   $form_state['rebuild_info']['copy']['#build_id'] = TRUE;
   $form_state['rebuild_info']['copy']['#action'] = TRUE;