Description:
------------
If code is run inside an array offset unset the reported size of that array will be off by one:

<?php

class Foo {
    public $array;

    public function __destruct() {
        var_dump(count($this->array[0]));
        var_dump($this->array[0]);
    }
}

$array = [[new Foo]];
$array[0][0]->array =& $array;
unset($array[0][0]);

Outputs:

int(1)
array(1) {
}

The reason is that zend_hash_del_key_or_index decrements the element count *after* calling the bucket dtor.