Description:
------------
When using array_unshift() on multidimension arrays there is a bug when index in array does not exists. When you have array with arrays inside like this:

$arr = array(
	array('ddddd'),
	array('eeee'),
	array('ffff'),
	array('gggg'),
);

and you use:

array_unshift($arr[4], 4);

this function not only show you warning message, but also add one element with null value to the end (!) of $arr array. It should not be working like that. It should show a warning and do nothing.

My version of PHP:
piotrekkr@piotrekkr-desktop:/var/www$ php -v
PHP 5.3.3-1ubuntu9.3 with Suhosin-Patch (cli) (built: Jan 12 2011 16:07:38) 
Copyright (c) 1997-2009 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies

OS: Ubuntu 10.10

Test script:
---------------
<?php
$arr = array(
	array('ddddd'),
	array('eeee'),
	array('ffff'),
	array('gggg'),
);
array_unshift($arr[4], 4);
print_r($arr);

Expected result:
----------------
PHP Warning:  array_unshift() expects parameter 1 to be array, null given in /var/www/unshift_test.php on line 9
Array
(
    [0] => Array
        (
            [0] => ddddd
        )

    [1] => Array
        (
            [0] => eeee
        )

    [2] => Array
        (
            [0] => ffff
        )

    [3] => Array
        (
            [0] => gggg
        )
)


Actual result:
--------------
PHP Warning:  array_unshift() expects parameter 1 to be array, null given in /var/www/unshift_test.php on line 9
Array
(
    [0] => Array
        (
            [0] => ddddd
        )

    [1] => Array
        (
            [0] => eeee
        )

    [2] => Array
        (
            [0] => ffff
        )

    [3] => Array
        (
            [0] => gggg
        )

    [4] => 
)