Index: modules/system/system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.624
diff -u -p -r1.624 system.module
--- modules/system/system.module	27 Sep 2008 19:47:43 -0000	1.624
+++ modules/system/system.module	27 Sep 2008 23:53:13 -0000
@@ -692,6 +692,17 @@ function system_init() {
   drupal_add_css(drupal_get_path('module', 'system') . '/defaults.css', 'module');
   drupal_add_css(drupal_get_path('module', 'system') . '/system.css', 'module');
   drupal_add_css(drupal_get_path('module', 'system') . '/system-menus.css', 'module');
+
+  // Check whether this user should not use a potential slave server
+  // for the current request.
+  if (isset($_SESSION['ignore_slave_server'])) {
+    if ($_SESSION['ignore_slave_server'] < REQUEST_TIME) {
+      Database::ignoreTarget('default', 'slave');
+    }
+    else {
+      unset($_SESSION['ignore_slave_server']);
+    }
+  }
 }
 
 /**