FIX: rss feed should be valid

app/views/list/list.rss.erb

@@ -11,7 +11,7 @@
       <lastBuildDate><%= @topic_list.topics.first.created_at.rfc2822 %></lastBuildDate>
       <atom:link href="<%= @atom_link %>" rel="self" type="application/rss+xml" />
       <% @topic_list.topics.each do |topic| %>
-        <% topic_url = topic.relative_url -%>
+        <% topic_url = topic.url -%>
         <item>
           <title><%= topic.title %></title>
           <author><%= "no-reply@example.com (@#{topic.user.username}#{" #{topic.user.name}" if (topic.user.name.present? && SiteSetting.enable_names?)})" -%></author>

app/views/topics/show.rss.erb

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8" ?>
 <rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
   <channel>
-    <% topic_url = @topic_view.relative_url %>
+    <% topic_url = @topic_view.absolute_url %>
     <% lang = SiteSetting.find_by_name('default_locale').try(:value) %>
     <% site_email = SiteSetting.find_by_name('contact_email').try(:value) %>
     <title><%= @topic_view.title %></title>
@@ -31,7 +31,7 @@
         <link><%= post_url %></link>
         <pubDate><%= post.created_at.rfc2822 %></pubDate>
         <guid isPermaLink="false">post-<%= post.topic_id %>-<%= post.post_number %></guid>
-        <source url="<%= @topic_view.relative_url %>.rss"><%= @topic_view.title %></source>
+        <source url="<%= @topic_view.absolute_url %>.rss"><%= @topic_view.title %></source>
       </item>
     <% end %>
   </channel>