Description:
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---
From manual page: http://www.php.net/function.session-start
---
I'm using session_start(); and some times when a $_SESSION param is EMPTY I get this error:

Warning: Unknown: Your script possibly relies on a session side-effect which existed until PHP 4.2.3. Please be advised that the session extension does not consider global variables as a source of data, unless register_globals is enabled. You can disable this functionality and this warning by setting session.bug_compat_42 or session.bug_compat_warn to off, respectively. in Unknown on line 0



Test script:
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session_start();
//error_reporting(0);
//session_unset ();


$_SESSION['product'] = $_SESSION['form'];//received from prev. page this is the bug when ['form'] is empty or not defined

include('do-csv.php');// save $_GET in a csv file
include('do-Scsv.php');// save $_SESSION in a csv file

Expected result:
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no warning should be output.

Actual result:
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Warning: Unknown: Your script possibly relies on a session side-effect which existed until PHP 4.2.3. Please be advised that the session extension does not consider global variables as a source of data, unless register_globals is enabled. You can disable this functionality and this warning by setting session.bug_compat_42 or session.bug_compat_warn to off, respectively. in Unknown on line 0