Update to drupal-org-drupal 8.0.0-rc2. For more information, see https://www.drupal.org/node/2598668

vendor/symfony/routing/Tests/Fixtures/validpattern.php

@@ -1,18 +0,0 @@
-<?php
-
-use Symfony\Component\Routing\RouteCollection;
-use Symfony\Component\Routing\Route;
-
-$collection = new RouteCollection();
-$collection->add('blog_show', new Route(
-    '/blog/{slug}',
-    array('_controller' => 'MyBlogBundle:Blog:show'),
-    array('locale' => '\w+'),
-    array('compiler_class' => 'RouteCompiler'),
-    '{locale}.example.com',
-    array('https'),
-    array('GET', 'POST', 'put', 'OpTiOnS'),
-    'context.getMethod() == "GET"'
-));
-
-return $collection;