Merged branch '4.4'

Author: alongosz

src/lib/MVC/Symfony/Controller/Content/PreviewController.php

@@ -130,8 +130,7 @@ public function previewContentAction(
                 throw $e;
             }
         }
-        $response->headers->remove('cache-control');
-        $response->headers->remove('expires');
+        $response->setPrivate();
 
         $this->previewHelper->restoreConfigScope();
         $this->previewHelper->setPreviewActive(false);