mysqli_change_user does not allow to use NULL for $database param

Description

According to the documentation, the third parameter in mysqli_change_user is nullable (not optional though) and passing NULL should connect to the same database.

If desired, the null value may be passed resulting in only changing the user and not selecting a database. To select a database in this case use the mysqli_select_db() function.

But to my knowledge this was never possible and is still not supported by mysqli. This code will reset database to NULL

$mysqli = new mysqli("localhost", "my_user", "my_password", "test");
$mysqli->change_user("my_user", "my_password", null);
var_dump($mysqli->query("SELECT DATABASE()")->fetch_row()[0]);

Resulted in this output:

NULL

But I expected this output instead:

string(4) "test"

PHP Version

All versions

Operating System

No response

Comienza por el punto de entrada mysqli_change_user y compara el comportamiento documentado de NULL con la reproducción de PHP proporcionada. Se considera completado cuando pasar NULL conserva la selección de base de datos existente y la reproducción confirma que SELECT DATABASE() sigue devolviendo "test".