Merged r73261 from branches/2.3

git-svn-id: svn://svn.silverstripe.com/silverstripe/open/modules/sapphire/branches/2.2@73401 467b73ca-7a2a-4603-9d3b-597d59a354a9

core/control/HTTPResponse.php

@@ -123,7 +123,7 @@ function output() {
 	 * Specifically, returns true if a redirect has already been requested
 	 */
 	function isFinished() {
-		return $this->statusCode == 302 || $this->statusCode == 301;
+		return in_array($this->statusCode, array(301, 302, 401, 403));
 	}
 
     /**