Issue #1334344 by jessebeach, mikestefff: Fixed During update, Bartik throws an error that () is not defined.

core/themes/bartik/template.php

@@ -73,8 +73,12 @@ function bartik_process_page(&$variables) {
  * Implements hook_preprocess_maintenance_page().
  */
 function bartik_preprocess_maintenance_page(&$variables) {
+  // By default, site_name is set to Drupal if no db connection is available
+  // or during site installation. Setting site_name to an empty string makes
+  // the site and update pages look cleaner.
+  // @see template_preprocess_maintenance_page
   if (!$variables['db_is_active']) {
-    unset($variables['site_name']);
+    $variables['site_name'] = '';
   }
   drupal_add_css(drupal_get_path('theme', 'bartik') . '/css/maintenance-page.css');
 }