BUGFIX: muted categories showing up in new via message bus

app/serializers/current_user_serializer.rb

@@ -22,7 +22,8 @@ class CurrentUserSerializer < BasicUserSerializer
              :should_be_redirected_to_top,
              :redirected_to_top_reason,
              :disable_jump_reply,
-             :custom_fields
+             :custom_fields,
+             :muted_category_ids
 
   def include_site_flagged_posts_count?
     object.staff?
@@ -93,4 +94,10 @@ class CurrentUserSerializer < BasicUserSerializer
     end
   end
 
+  def muted_category_ids
+    @muted_category_ids ||= CategoryUser.where(user_id: object.id,
+                                               notification_level: TopicUser.notification_levels[:muted])
+                                         .pluck(:category_id)
+  end
+
 end