Index: trunk/wp-includes/comment-functions.php
===================================================================
--- trunk/wp-includes/comment-functions.php	(revision 3425)
+++ trunk/wp-includes/comment-functions.php	(working copy)
@@ -214,7 +214,7 @@
 
 function clean_url( $url ) {
 	if ('' == $url) return $url;
-	$url = preg_replace('|[^a-z0-9-~+_.?#=&;,/:]|i', '', $url);
+	$url = preg_replace('|[^a-z0-9-~+_.?#=&;,/:%]|i', '', $url);
 	$url = str_replace(';//', '://', $url);
 	$url = (!strstr($url, '://')) ? 'http://'.$url : $url;
 	$url = preg_replace('/&([^#])(?![a-z]{2,8};)/', '&$1', $url);