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

vendor/symfony/http-kernel/DependencyInjection/MergeExtensionConfigurationPass.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\HttpKernel\DependencyInjection;
+
+use Symfony\Component\DependencyInjection\Compiler\MergeExtensionConfigurationPass as BaseMergeExtensionConfigurationPass;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+
+/**
+ * Ensures certain extensions are always loaded.
+ *
+ * @author Kris Wallsmith <kris@symfony.com>
+ */
+class MergeExtensionConfigurationPass extends BaseMergeExtensionConfigurationPass
+{
+    private $extensions;
+
+    public function __construct(array $extensions)
+    {
+        $this->extensions = $extensions;
+    }
+
+    public function process(ContainerBuilder $container)
+    {
+        foreach ($this->extensions as $extension) {
+            if (!count($container->getExtensionConfig($extension))) {
+                $container->loadFromExtension($extension, array());
+            }
+        }
+
+        parent::process($container);
+    }
+}