When using non-ascii characters for the filename in Response::download an InvalidArgumentException will be raised with the text The filename fallback must only contain ASCII characters. in ResponseHeaderBag.php:266.

Apparently only ascii characters are valid for the filename. Why can this be? Should unicode not be allowed? Why put in this barrier?

    // filenameFallback is not ASCII.
    if (!preg_match('/^[\x20-\x7e]*$/', $filenameFallback)) {
        throw new \InvalidArgumentException('The filename fallback must only contain ASCII characters.');
    }