The global variable scope doesn't work with 3.9.2

At the root of the eZ publish install create a file test.php

<?php
$a = 1;
$b = 2;

function Sum()
{
    global $a, $b;

    $b = $a + $b;
}

Sum();
echo $b;
?> 

run php test.php
You got 3

Replace the content of cronjobs/workflow.php by the same piece of code
run php runcronjobs.php frequent
You got 2 !!!
If you do the same test with eZ publish 3.9.0 or 3.9.1 you have the correct answer (3)
What happened to the global scope of a php variable in eZ 3.9.2 (it doesn't work either with latest svn code)!!!

Steps to reproduce

See above