fixed weird redirect under nginx proxy_pass over apache2

lib/php/dashboard.php

@@ -1,6 +1,7 @@
 <?php
     if ( ! isset ( $_SESSION [ 'user_id' ] ) ) {
         header ( "Location: " . $GLOBALS [ 'config' ] [ 'installation_path' ] . "/login" );
+        exit;
     }
     if ( isset ( $GLOBALS [ 'request_uri' ] [ 1 ] ) ) {
         switch ( $GLOBALS [ 'request_uri' ] [ 1 ] ) {