Update to drupal 8.0.0-rc1. For more information, see https://www.drupal.org/node/2582663

vendor/symfony/http-foundation/Session/Storage/Proxy/NativeProxy.php

@@ -0,0 +1,41 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\HttpFoundation\Session\Storage\Proxy;
+
+/**
+ * NativeProxy.
+ *
+ * This proxy is built-in session handlers in PHP 5.3.x
+ *
+ * @author Drak <drak@zikula.org>
+ */
+class NativeProxy extends AbstractProxy
+{
+    /**
+     * Constructor.
+     */
+    public function __construct()
+    {
+        // this makes an educated guess as to what the handler is since it should already be set.
+        $this->saveHandlerName = ini_get('session.save_handler');
+    }
+
+    /**
+     * Returns true if this handler wraps an internal PHP session save handler using \SessionHandler.
+     *
+     * @return bool False.
+     */
+    public function isWrapper()
+    {
+        return false;
+    }
+}