Rely only on moodle registered shutdown handlers to save the session

extlib/simplesamlphp/lib/SimpleSAML/Logger.php

@@ -341,6 +341,7 @@ private static function defer($level, $message, $stats)
         // save the message for later
         self::$earlyLog[] = array('level' => $level, 'string' => $message, 'statsLog' => $stats);
 
+
         // register a shutdown handler if needed
         if (!self::$shutdownRegistered) {
             register_shutdown_function(array('SimpleSAML\Logger', 'flush'));

extlib/simplesamlphp/lib/SimpleSAML/Session.php

@@ -490,6 +490,10 @@ public function markDirty()
 
         $this->dirty = true;
 
+        // Moodle auth_saml2 hack, because we register a shutdown handler in
+        // moodle in the constructor we don't need to register a callback here.
+        return;
+
         if (!function_exists('header_register_callback')) {
             // PHP version < 5.4, can't register the callback
             return;
@@ -511,7 +515,9 @@ public function markDirty()
      */
     public function __destruct()
     {
-        $this->save();
+        // Moodle auth_saml2 hack, we don't need to save here because we have
+        // a custom shutdown handle registered with moodle.
+        // $this->save();
     }
 
     /**