Index: modules/system/system.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.install,v
retrieving revision 1.422
diff -u -p -r1.422 system.install
--- modules/system/system.install	11 Nov 2009 17:06:30 -0000	1.422
+++ modules/system/system.install	1 Dec 2009 07:52:53 -0000
@@ -2498,10 +2498,10 @@ function system_update_7030() {
 }
 
 /**
- * Add a missing index on the {menu_router} table.
+ * Removed in favour of Drupal 6 backport.
+ * @see system_update_6052()
  */
 function system_update_7031() {
-  db_add_index('menu_router', 'tab_root_weight_title', array(array('tab_root', 64), 'weight', 'title'));
 }
 
 /**