Description:
------------
Hi,
please refer the source code below...
I wonder why there is a variable 'sesClientIP' been auto generated.

To get the thing appear, follow the step:
1. go to the page that contain the source code below. 
   ** you will see the Expected result.
2. go to another web site e.g. google.com.
3. press 'back' button, and then press 'refresh' button if using Firefox.
   ** you will able to see there is a variable 'sesClientIP' in the $_SESSION.

I am expecting there will no any data in the $_SESSION.
Please correct me if I am wrong.
Note: there was no reference can be found from Yahoo or Google.

Reproduce code:
---------------
<?php
session_start();
echo "<pre>";
var_export($_SESSION);
echo "</pre>";
?>

Expected result:
----------------
array (
)


Actual result:
--------------
array (
  'sesClientIP' => '',
)