Index: modules/system/system.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.admin.inc,v
retrieving revision 1.188
diff -u -p -r1.188 system.admin.inc
--- modules/system/system.admin.inc	22 Aug 2009 20:01:10 -0000	1.188
+++ modules/system/system.admin.inc	23 Aug 2009 08:19:45 -0000
@@ -1306,12 +1306,6 @@ function system_site_information_setting
     '#description' => t('This page is displayed when no other content matches the requested document. Leave blank to display a generic "page not found" page.'),
     '#field_prefix' => url(NULL, array('absolute' => TRUE)) . (variable_get('clean_url', 0) ? '' : '?q=')
   );
-  $form['site_404_blocks'] = array(
-    '#type' => 'checkbox',
-    '#title' => t('Display blocks on default 404 (not found) page'),
-    '#description' => t('Render all blocks on the default 404 (not found) page. Disabling blocks can help with performance but might leave users with a less functional site.'),
-    '#default_value' => variable_get('site_404_blocks', 0)
-  );
   $form['cron_safe_threshold'] = array(
     '#type' => 'select',
     '#title' => t('Automatically run cron'),
Index: modules/system/system.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.install,v
retrieving revision 1.376
diff -u -p -r1.376 system.install
--- modules/system/system.install	22 Aug 2009 18:24:14 -0000	1.376
+++ modules/system/system.install	23 Aug 2009 08:19:49 -0000
@@ -2456,6 +2456,18 @@ function system_update_7036() {
 }
 
 /**
+ * Delete obsolete variable 'site_404_blocks'.
+ */
+function system_update_7037() {
+  $ret = array();
+
+  // Remove obsolete variable 'site_404_blocks'.
+  variable_del('site_404_blocks');
+
+  return $ret;
+}
+
+/**
  * @} End of "defgroup updates-6.x-to-7.x"
  * The next series of updates should start at 8000.
  */
Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.968
diff -u -p -r1.968 common.inc
--- includes/common.inc	22 Aug 2009 19:58:27 -0000	1.968
+++ includes/common.inc	23 Aug 2009 08:19:52 -0000
@@ -422,12 +422,7 @@ function drupal_not_found() {
     $return = t('The requested page could not be found.');
   }
 
-  drupal_set_page_content($return);
-  $page = element_info('page');
-  // Optionally omit the blocks to conserve CPU and bandwidth.
-  $page['#show_blocks'] = variable_get('site_404_blocks', FALSE);
-
-  print drupal_render_page($page);
+  print drupal_render_page($return);
 }
 
 /**