Index: includes/menu.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/menu.inc,v
retrieving revision 1.255.2.31
diff -u -p -r1.255.2.31 menu.inc
--- includes/menu.inc	27 Apr 2009 12:50:13 -0000	1.255.2.31
+++ includes/menu.inc	16 Aug 2009 01:44:56 -0000
@@ -1891,7 +1891,12 @@ function menu_link_save(&$item) {
     $existing_item = db_fetch_array(db_query("SELECT * FROM {menu_links} WHERE mlid = %d", $item['mlid']));
   }
 
-  if (isset($item['plid'])) {
+  // If no explicit plid is defined as parent, then the the re-parenting process
+  // is always invoked, since there is no guarantee that a plid of 0 is not
+  // caused by a re-parenting process that went wrong previously. For example,
+  // local tasks may be re-parented to the top-level (0) when tab_root points to
+  // an item of type MENU_CALLBACK.
+  if (!empty($item['plid'])) {
     $parent = db_fetch_array(db_query("SELECT * FROM {menu_links} WHERE mlid = %d", $item['plid']));
   }
   else {
@@ -1918,6 +1923,14 @@ function menu_link_save(&$item) {
         $parent = db_fetch_array(db_query("SELECT * FROM {menu_links} ". $where, $parent_path, $arg2));
       }
     } while ($parent === FALSE && $parent_path);
+
+    // Whenever we retrieve a menu link for a router item from the database, we
+    // need to update the menu link properties according to the new router item.
+    // Otherwise, the re-parenting process gets stuck on the menu router data
+    // that was stored in {menu_links} in the previous rebuild.
+    if ($parent && !empty($parent['router_path']) && isset($menu[$parent['router_path']])) {
+      $parent = array_merge($parent, _menu_link_build($parent));
+    }
   }
   if ($parent !== FALSE) {
     $item['menu_name'] = $parent['menu_name'];