Index: modules/system/system.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.install,v
retrieving revision 1.219
diff -u -p -r1.219 system.install
--- modules/system/system.install	27 Dec 2007 17:25:28 -0000	1.219
+++ modules/system/system.install	28 Dec 2007 20:57:00 -0000
@@ -2278,7 +2278,7 @@ function system_update_6043() {
   db_drop_index($ret, 'node', 'status');
   db_drop_unique_key($ret, 'node', 'nid_vid');
   // Improve user module indices.
-  db_add_unique_key($ret, 'users', 'mail', array('mail'));
+  db_add_index($ret, 'users', 'mail', array('mail'));
   db_add_index($ret, 'users_roles', 'rid', array('rid'));
 
   // Optional modules - need to check if the tables exist.
Index: modules/user/user.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.install,v
retrieving revision 1.4
diff -u -p -r1.4 user.install
--- modules/user/user.install	18 Dec 2007 12:59:22 -0000	1.4
+++ modules/user/user.install	28 Dec 2007 20:57:00 -0000
@@ -252,11 +252,11 @@ function user_schema() {
     ),
     'indexes' => array(
       'access' => array('access'),
-      'created' => array('created')
+      'created' => array('created'),
+      'mail' => array('mail'),
     ),
     'unique keys' => array(
       'name' => array('name'),
-      'mail' => array('mail'),
     ),
     'primary key' => array('uid'),
   );