fix error

lib/feed_model/cache.rb

@@ -7,6 +7,10 @@ module FeedModel
       before_save :do_before_save
     end
     def recreate_annc_cache(feed)
+      count = SiteFeedAnnc.where(feed_id: feed.id).count
+      if count>1
+        SiteFeedAnnc.where(feed_id: feed.id).limit(count-1).destroy
+      end
       tmp = SiteFeedAnnc.where(feed_id: feed.id).first
       if tmp.nil?
         tmp = SiteFeedAnnc.new(feed_id: feed.id)