Issue #2238945 by effulgentsia: Remove the 'clean_urls' request attribute.

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

@@ -50,13 +50,7 @@ public function onKernelRequestConvertPath(GetResponseEvent $event) {
     $path = trim($request->getPathInfo(), '/');
     $path = $this->pathProcessor->processInbound($path, $request);
     $request->attributes->set('_system_path', $path);
-    // Also set an attribute that indicates whether we are using clean URLs.
-    $clean_urls = TRUE;
-    $base_url = $request->getBaseUrl();
-    if (!empty($base_url) && strpos($base_url, $request->getScriptName()) !== FALSE) {
-      $clean_urls = FALSE;
-    }
-    $request->attributes->set('clean_urls', $clean_urls);
+
     // Set the cache key on the alias manager cache decorator.
     if ($event->getRequestType() == HttpKernelInterface::MASTER_REQUEST) {
       $this->aliasManager->setCacheKey($path);

core/lib/Drupal/Core/Routing/RequestHelper.php

@@ -128,4 +128,25 @@ public static function duplicate(Request $original_request, $uri, $method = 'GET
     return $request;
   }
 
+  /**
+   * Returns whether the request is using a clean URL.
+   *
+   * A clean URL is one that does not include the script name. For example,
+   * - http://example.com/node/1 is a clean URL.
+   * - http://example.com/index.php/node/1 is not a clean URL.
+   *
+   * Unclean URLs are required on sites hosted by web servers that cannot be
+   * configured to implicitly route URLs to index.php.
+   *
+   * @param \Symfony\Component\HttpFoundation\Request $request
+   *   The request.
+   *
+   * @return bool
+   *   TRUE if the request is using a clean URL.
+   */
+  public static function isCleanUrl(Request $request) {
+    $base_url = $request->getBaseUrl();
+    return (empty($base_url) || strpos($base_url, $request->getScriptName()) === FALSE);
+  }
+
 }

core/modules/image/lib/Drupal/image/Entity/ImageStyle.php

@@ -10,6 +10,7 @@
 use Drupal\Core\Config\Entity\ConfigEntityBase;
 use Drupal\Core\Config\Entity\EntityWithPluginBagInterface;
 use Drupal\Core\Entity\EntityStorageInterface;
+use Drupal\Core\Routing\RequestHelper;
 use Drupal\image\ImageEffectBag;
 use Drupal\image\ImageEffectInterface;
 use Drupal\image\ImageStyleInterface;
@@ -208,7 +209,7 @@ public function buildUrl($path, $clean_urls = NULL) {
       $clean_urls = TRUE;
       try {
         $request = \Drupal::request();
-        $clean_urls = $request->attributes->get('clean_urls');
+        $clean_urls = RequestHelper::isCleanUrl($request);
       }
       catch (ServiceNotFoundException $e) {
       }