Index: system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.585.2.21
diff -u -r1.585.2.21 system.module
--- system.module	8 Oct 2008 20:47:04 -0000	1.585.2.21
+++ system.module	16 Oct 2008 09:29:28 -0000
@@ -762,7 +762,7 @@
     if (isset($files[$file->name]) && is_object($files[$file->name])) {
       $file->old_filename = $file->filename;
       foreach ($file as $key => $value) {
-        if (!isset($files[$file->name]) || !isset($files[$file->name]->$key)) {
+        if (!isset($files[$file->name]) || !isset($files[$file->name]->$key) || (defined('MAINTENANCE_MODE') && MAINTENANCE_MODE == 'update')) {
           $files[$file->name]->$key = $value;
         }
       }