Fix case where port is missing

Forward port of 6d3b5b24fd to master

lib/private/request.php

@@ -59,7 +59,7 @@ class OC_Request {
 			if (isset($_SERVER['HTTP_HOST'])) {
 				$host = $_SERVER['HTTP_HOST'];
 			}
-			if (isset($_SERVER['SERVER_NAME'])) {
+			else if (isset($_SERVER['SERVER_NAME'])) {
 				$host = $_SERVER['SERVER_NAME'];
 			}
 		}