Merge branch '2.8' into 3.3

* 2.8:
  Remove function_exists(__phpunit_run_isolated_test) checks

Author: nicolas-grekas

Tests/Fixtures/validresource.php

@@ -1,8 +1,5 @@
 <?php
 
-if (function_exists('__phpunit_run_isolated_test')) {
-    return;
-}
 /** @var $loader \Symfony\Component\Routing\Loader\PhpFileLoader */
 /** @var \Symfony\Component\Routing\RouteCollection $collection */
 $collection = $loader->import('validpattern.php');