[Console] added mb_detect_encoding when needed

src/Symfony/Component/Console/Application.php

@@ -697,7 +697,7 @@ class Application
     {
         $strlen = function ($string)
         {
-            return function_exists('mb_strlen') ? mb_strlen($string) : strlen($string);
+            return function_exists('mb_strlen') ? mb_strlen($string, mb_detect_encoding($string)) : strlen($string);
         };
 
         do {