Issue #3066455: Resolve relative URLs to their appropriate alias

Closes #3066455

src/Plugin/RulesAction/SystemPageRedirect.php

@@ -2,9 +2,11 @@
 
 namespace Drupal\rules\Plugin\RulesAction;
 
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\Core\Logger\LoggerChannelInterface;
 use Drupal\Core\Path\CurrentPathStack;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\Url;
 use Drupal\rules\Core\RulesActionBase;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\HttpFoundation\RequestStack;
@@ -107,6 +109,9 @@ class SystemPageRedirect extends RulesActionBase implements ContainerFactoryPlug
       return;
     }
 
+    if (!UrlHelper::isExternal($url)) {
+      $url = Url::fromUserInput('/' . ltrim($url, '/'))->toString(TRUE)->getGeneratedUrl();
+    }
     $this->request->attributes->set('_rules_redirect_action_url', $url);
   }