diff -u b/core/lib/Drupal/Core/DependencyInjection/ContainerBuilder.php b/core/lib/Drupal/Core/DependencyInjection/ContainerBuilder.php
--- b/core/lib/Drupal/Core/DependencyInjection/ContainerBuilder.php
+++ b/core/lib/Drupal/Core/DependencyInjection/ContainerBuilder.php
@@ -94,0 +95,9 @@
+   * {@inheritdoc}
+   */
+  public function setAlias($alias, $id) {
+    $alias = parent::setAlias($alias, $id);
+    $alias->setPublic(TRUE);
+    return $alias;
+  }
+
+  /**
only in patch2:
unchanged:
--- a/core/modules/comment/tests/src/Functional/CommentPreviewTest.php
+++ b/core/modules/comment/tests/src/Functional/CommentPreviewTest.php
@@ -117,6 +117,8 @@ public function testCommentPreviewDuplicateSubmission() {
 
     // Go back and re-submit the form.
     $this->getSession()->getDriver()->back();
+    $submit_button = $this->assertSession()->buttonExists('Save');
+    $submit_button->click();
     $this->assertText('Your comment has been posted.');
     $elements = $this->xpath('//section[contains(@class, "comment-wrapper")]/article');
     $this->assertEqual(2, count($elements));