Revert "login: only allow relative URLs in return="

This reverts commit c68ac04020.

classes/handler/public.php

@@ -712,10 +712,8 @@ class Handler_Public extends Handler {
 				user_error("Failed login attempt for $login from {$_SERVER['REMOTE_ADDR']}", E_USER_WARNING);
 			}
 
-			$return = clean($_REQUEST['return']);
-
-			if ($return && !is_absolute_url($return)) {
-				header("Location: " . $return);
+			if (clean($_REQUEST['return'])) {
+				header("Location: " . clean($_REQUEST['return']));
 			} else {
 				header("Location: " . get_self_url_prefix());
 			}

include/functions.php

@@ -2562,9 +2562,3 @@
 
 		return $ts;
 	}
-
-	function is_absolute_url($url) {
-		$parts = parse_url($url);
-
-		return $parts['host'] != '';
-	}