--- drupal-6.16/includes/common.inc.orig	2010-03-03 19:15:28.000000000 -0500
+++ drupal-6.16/includes/common.inc	2010-04-06 09:34:47.000000000 -0400
@@ -3692,14 +3692,7 @@
   drupal_clear_css_cache();
   drupal_clear_js_cache();
 
-  // If invoked from update.php, we must not update the theme information in the
-  // database, or this will result in all themes being disabled.
-  if (defined('MAINTENANCE_MODE') && MAINTENANCE_MODE == 'update') {
-    _system_theme_data();
-  }
-  else {
-    system_theme_data();
-  }
+  system_theme_data();
 
   drupal_rebuild_theme_registry();
   menu_rebuild();
--- drupal-6.16/modules/system/system.module.orig	2010-04-06 09:33:03.000000000 -0400
+++ drupal-6.16/modules/system/system.module	2010-04-06 09:36:10.000000000 -0400
@@ -809,6 +809,11 @@
   // Scan the installation theme .info files and their engines.
   $themes = _system_theme_data();
 
+  // If invoked from update.php, we must not update the theme information in the
+  // database, or this will result in all themes being disabled.
+  if (defined('MAINTENANCE_MODE') && MAINTENANCE_MODE == 'update')
+    return $themes;
+
   // Extract current files from database.
   system_get_files_database($themes, 'theme');