Index: wp-includes/general-template.php
===================================================================
--- wp-includes/general-template.php	(revision 17522)
+++ wp-includes/general-template.php	(working copy)
@@ -1701,7 +1701,7 @@
  */
 function noindex() {
 	// If the blog is not public, tell robots to go away.
-	if ( '0' == get_option('blog_public') )
+	if ( isset($_GET['replytocom']) || '0' == get_option('blog_public') )
 		echo "<meta name='robots' content='noindex,nofollow' />\n";
 }