Description:
------------
I write some code in charset "GBK" and use session to store some text.
When I get the $_SESSION data, found it's UTF-8, which behave different 
from PHP5.2.x

Reproduce code:
---------------
test.php (ASNI)
================
<?php
session_start();

$_SESSION['name'] = '??????';

echo $_SESSION['name'];

?>

Expected result:
----------------
display:
=========
??????

Actual result:
--------------
display:
=========
text can't viewed  correctly in charset "GBK".