diff --git a/core/modules/forum/forum.admin.inc b/core/modules/forum/forum.admin.inc
index 8ae054d..7c52780 100644
--- a/core/modules/forum/forum.admin.inc
+++ b/core/modules/forum/forum.admin.inc
@@ -136,11 +136,11 @@ function forum_form_submit($form, &$form_state) {
  *   - form: A render element representing the form.
  */
 function template_preprocess_forum_form(&$variables) {
-  foreach ($variables['form'] as $key => $value) {
-    // Prevent recursion loop by removing '#theme' and '#theme_wrappers' keys.
-    // See http://drupal.org/node/1920886.
-    if ($key == '#theme' || $key == '#theme_wrappers') {
-      unset($variables['form'][$key]);
+  // Prevent recursion loop by removing '#theme' and '#theme_wrappers' keys.
+  // See http://drupal.org/node/1920886.
+  foreach (array('#theme', '#theme_wrappers') as $theme_key) {
+    if (isset($variables['form'][$theme_key])) {
+      unset($variables['form'][$theme_key]);
     }
   }
 }
diff --git a/core/modules/forum/templates/forum-list.html.twig b/core/modules/forum/templates/forum-list.html.twig
index 6de5c11..6e5f6da 100644
--- a/core/modules/forum/templates/forum-list.html.twig
+++ b/core/modules/forum/templates/forum-list.html.twig
@@ -7,21 +7,21 @@
  * - forums: A list of forums and containers to display. It is keyed to the
  *   numeric IDs of all child forums and containers. Each forum in forums
  *   contains:
- *   - forum.is_container: A flag indicating if the forum can contain other
+ *   - is_container: A flag indicating if the forum can contain other
  *     forums. Otherwise, the forum can only contain topics.
- *   - forum.depth: How deep the forum is in the current hierarchy.
- *   - forum.zebra: 'even' or 'odd', used for row class.
- *   - forum.icon_class: 'default' or 'new', used for forum icon class.
- *   - forum.icon_title: Text alternative for the forum icon.
- *   - forum.name: The name of the forum.
- *   - forum.link: The URL to link to this forum.
- *   - forum.description: The description of this forum.
- *   - forum.new_topics: A flag indicating if the forum contains unread posts.
- *   - forum.new_url: A URL to the forum's unread posts.
- *   - forum.new_text: Text for the above URL, which tells how many new posts.
- *   - forum.old_topics: A count of posts that have already been read.
- *   - forum.num_posts: The total number of posts in the forum.
- *   - forum.last_reply: Text representing the last time a forum was posted or
+ *   - depth: How deep the forum is in the current hierarchy.
+ *   - zebra: 'even' or 'odd', used for row class.
+ *   - icon_class: 'default' or 'new', used for forum icon class.
+ *   - icon_title: Text alternative for the forum icon.
+ *   - name: The name of the forum.
+ *   - link: The URL to link to this forum.
+ *   - description: The description of this forum.
+ *   - new_topics: A flag indicating if the forum contains unread posts.
+ *   - new_url: A URL to the forum's unread posts.
+ *   - new_text: Text for the above URL, which tells how many new posts.
+ *   - old_topics: A count of posts that have already been read.
+ *   - num_posts: The total number of posts in the forum.
+ *   - last_reply: Text representing the last time a forum was posted or
  *     commented in.
  * - forum_id: Forum ID for the current forum. Parent to all items within the
  *   forums array.
diff --git a/core/modules/forum/templates/forum-topic-list.html.twig b/core/modules/forum/templates/forum-topic-list.html.twig
index dc2c4ed..59ac9fe 100644
--- a/core/modules/forum/templates/forum-topic-list.html.twig
+++ b/core/modules/forum/templates/forum-topic-list.html.twig
@@ -9,23 +9,20 @@
  *   template_preprocess_forum_topic_list().
  * - pager: The pager to display beneath the table.
  * - topics: A list of topics to be displayed. Each topic in topics contains:
- *   - topic.icon: The icon to display.
- *   - topic.moved: A flag to indicate whether the topic has been moved to
- *     another forum.
- *   - topic.title: The title of the topic. Safe to output.
- *   - topic.message: If the topic has been moved, this contains an
- *     explanation and a link.
- *   - topic.zebra: 'even' or 'odd', used for row class.
- *   - topic.comment_count: The number of replies on this topic.
- *   - topic.new_replies: A flag to indicate whether there are unread
- *     comments.
- *   - topic.new_url: If there are unread replies, this is a link to them.
- *   - topic.new_text: Text containing the translated, properly pluralized
- *     count.
- *   - topic.created: Text representing when the topic was posted. Safe to
- *     output.
- *   - topic.last_reply: Text representing when the topic was last replied to.
- *   - topic.timestamp: The raw timestamp this topic was posted.
+ *   - icon: The icon to display.
+ *   - moved: A flag to indicate whether the topic has been moved to another
+ *     forum.
+ *   - title: The title of the topic. Safe to output.
+ *   - message: If the topic has been moved, this contains an explanation and a
+ *     link.
+ *   - zebra: 'even' or 'odd', used for row class.
+ *   - comment_count: The number of replies on this topic.
+ *   - new_replies: A flag to indicate whether there are unread comments.
+ *   - new_url: If there are unread replies, this is a link to them.
+ *   - new_text: Text containing the translated, properly pluralized count.
+ *   - created: Text representing when the topic was posted. Safe to output.
+ *   - last_reply: Text representing when the topic was last replied to.
+ *   - timestamp: The raw timestamp this topic was posted.
  * - topic_id: Numeric ID for the current forum topic.
  *
  * @see template_preprocess()