if we're doing feeds, we shall not send 'always modified' headers

git-svn-id: http://svn.automattic.com/wordpress/trunk@909 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-blog-header.php

@@ -73,6 +73,8 @@ $wpvarstoreset = array('m','p','posts','w', 'cat','withcomments','s','search','e
 
 
 /* Sending HTTP headers */
+
+if (!isset($doing_rss) || !$doing_rss) {
 	// It is presumptious to think that WP is the only thing that might change on the page.
 	@header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");                 // Date in the past
 	@header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); // always modified
@@ -80,6 +82,11 @@ $wpvarstoreset = array('m','p','posts','w', 'cat','withcomments','s','search','e
 	@header("Cache-Control: post-check=0, pre-check=0", false);
 	@header("Pragma: no-cache");                                     // HTTP/1.0
 	@header ("X-Pingback: $siteurl/xmlrpc.php");
+} else {
+	// We're showing a feed, so WP is indeed the only thing that last changed
+	@header('Last Modified: ' . gmdate(get_lastpostmodified()));
+	@header ("X-Pingback: $siteurl/xmlrpc.php");
+}
 
 /* Getting settings from db */
 if (isset($doing_rss) && $doing_rss == 1)