FIX: unpinned topics shouldn't remain pinned on categories page

lib/topic_query.rb

@@ -135,9 +135,10 @@ class TopicQuery
   def list_category_topic_ids(category)
     query = default_results(category: category.id)
     pinned_ids = query.where('pinned_at IS NOT NULL AND category_id = ?', category.id)
+                      .limit(nil)
                       .order('pinned_at DESC').pluck(:id)
     non_pinned_ids = query.where('pinned_at IS NULL OR category_id <> ?', category.id).pluck(:id)
-    (pinned_ids + non_pinned_ids)[0...@options[:per_page]]
+    (pinned_ids + non_pinned_ids)
   end
 
   def list_new_in_category(category)