Description:
------------
Some PHP legacy code no longer works with the 5.3.3 MYSQLND-enabled [1] PDO MySQL driver -- I got 2 warnings and an exception is raised:

[07-Sep-2010 14:31:16] PHP Warning: PDO::__construct(): Premature end of data (mysqlnd_wireprotocol.c:554) in /my/path/to/php/auto/append.php on line xx
[07-Sep-2010 14:31:16] PHP Warning: PDO::__construct(): OK packet 1 bytes shorter than expected in /my/path/to/php/auto/append.php on line xx

Exception says that "mysqlnd cannot connect to MySQL 4.1+ using the old insecure authentication."

This is inconsistent with the behavior of the 5.3.3 MySQL extension built with MYSQLND support: I have even older PHP code that can connect to MySQL 4.1+ using the old insecure authentication scheme (!?) Go figure.

Of course, reverting to the PDO MySQL driver w/ classic MySQL client library support works.

[1] mysqlnd 5.0.7-dev - 091210 - $Revision: 300533 $


Test script:
---------------
<?php

try {

    $dbh = new PDO($sql->dsn, $sql->username, $sql->password);
    $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

}
catch (Exception $e) { /* ... */ }
// failure
?>

vs.

<?php

$dbh = mysql_pconnect(
	$mysql['hostname'], $mysql['username'], $mysql['password']
);
// success
?>

Expected result:
----------------
Why does old password authentication still works with MYSQLND-enabled MySQL extension but not with MYSQLND-enabled PDO MySQL driver?

Actual result:
--------------
SQLSTATE[HY000] [2000] mysqlnd cannot connect to MySQL 4.1+ using the old insecure authentication. Please use an administration tool to reset your password with the command SET PASSWORD = PASSWORD('your_existing_password'). This will store a new, and more secure, hash value in mysql.user. If this user is used in other scripts executed by PHP 5.2 or earlier you might need to remove the old-passwords flag from your my.cnf file