Add BC shiv to keep old-style Dirty URLs working. This should be a temporary fix only, and be removed later.

core/lib/Drupal/Core/EventSubscriber/PathSubscriber.php

@@ -31,10 +31,17 @@ class PathSubscriber implements EventSubscriberInterface {
    *   The Event to process.
    */
   public function onKernelRequestPathResolve(GetResponseEvent $event) {
+
     $request = $event->getRequest();
 
     $path = ltrim($request->getPathInfo(), '/');
 
+    // Temporary BC shiv to support automated tests that still rely on old-
+    // style dirty URLs.
+    if (isset($_GET['q'])) {
+      $path = $_GET['q'];
+    }
+
     if (empty($path)) {
       // @todo Temporary hack. Fix when configuration is injectable.
       $path = variable_get('site_frontpage', 'user');

core/lib/Drupal/Core/UrlMatcher.php

@@ -38,6 +38,15 @@ class UrlMatcher extends SymfonyUrlMatcher {
     // Symfony uses a prefixing / but we don't yet.
     $dpathinfo = ltrim($pathinfo, '/');
 
+    // Temporary BC shiv to support automated tests that still rely on old-
+    // style dirty URLs.
+    // @todo Remove this once testbot knows how to deal with Symfony-style
+    // dirty URLs.
+    if (isset($_GET['q'])) {
+      $dpathinfo = $_GET['q'];
+      $pathinfo = '/' . $dpathinfo;
+    }
+
     // Do our fancy frontpage logic.
     if (empty($dpathinfo)) {
       $dpathinfo = variable_get('site_frontpage', 'user');