Index: modules/system/system.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.install,v
retrieving revision 1.389
diff -u -p -r1.389 system.install
--- modules/system/system.install	20 Sep 2009 17:56:24 -0000	1.389
+++ modules/system/system.install	28 Sep 2009 15:23:04 -0000
@@ -2046,6 +2046,7 @@ function system_update_7017() {
 function system_update_7018() {
   $ret = array();
   db_drop_index($ret, 'system', 'modules');
+  db_drop_index($ret, 'system', 'type_name');
   db_change_field($ret, 'system', 'type', 'type', array('type' => 'varchar', 'length' => 12, 'not null' => TRUE, 'default' => ''));
   db_add_index($ret, 'system', 'modules', array('type', 'status', 'weight', 'name'));
   db_add_index($ret, 'system', 'type_name', array('type', 'name'));