I'm not actually using version 4.0CVS-2001-11-14, but I updated 2001-11-08 (6 days ago) so I assume it's still in the source as no bugs reports detail this:

[mini:pgl]:~ $ php -v
4.2.0-dev
[mini:pgl]:~ $ cat ./test.php 
#!/usr/local/bin/php -q 
<?
$a = array('1', '2');
unset($a[]);
?>

[mini:pgl]:~ $ ./test.php 
Segmentation fault (core dumped)

regards,

Peter Lowe.