Index: includes/bootstrap.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/bootstrap.inc,v
retrieving revision 1.409
diff -u -p -r1.409 bootstrap.inc
--- includes/bootstrap.inc	10 Jul 2010 17:27:50 -0000	1.409
+++ includes/bootstrap.inc	16 Jul 2010 05:13:31 -0000
@@ -2928,6 +2928,10 @@ function &drupal_static($name, $default_
       return $data;
     }
   }
+  elseif (isset($data[$name])) {
+    // If variable is set and non-NULL, return it (avoiding array_key_exists).
+    return $data[$name];
+  }
   elseif (!array_key_exists($name, $data)) {
     // Store the default value internally and also copy it to the reference to
     // be returned.