Index: wp-includes/feed.php
===================================================================
--- wp-includes/feed.php	(revision 11140)
+++ wp-includes/feed.php	(working copy)
@@ -550,6 +550,7 @@
 	$feed->set_cache_class('WP_Feed_Cache');
 	$feed->set_file_class('WP_SimplePie_File');
 	$feed->set_cache_duration(43200);
+	$feed->force_feed(true);
 	$feed->init();
 	$feed->handle_content_type();