Description:
------------
apc include_once_override is not implemented properly. 

access following test script more than twice, will result a fatal error

Test script:
---------------
index.php:
<?php
set_include_path("/tmp");
function a($arg = array()) {
    include_once("b.php");
}

a();
a();
?>

/tmp/b.php
<?php
class B {
}
?>

Expected result:
----------------
works well

Actual result:
--------------
Fatal error: include(): Cannot redeclare class b