Description:
------------
I've used a little code snippet to convert property from value type to reference type. It's described here: http://www.php.net/manual/en/language.oop5.cloning.php
It's very useful practice when you want to share some properties between all clones. But it works with some bugs. When you try to read a reference type property of object without clones, this property unexpectedly converted to value type property.

Test script:
---------------
<?php
header('content-type: text/plain; charset=utf-8');

class demo
{
    public $n = 0;
    function __construct() { $this->n =& $this->n; }
    function magic()       { if ($this->n) return; }
    function set($n)       { $this->n = $n; }
}

// Outputs 1 = 1 as expected
$a1 = new demo();
$b1 = clone $a1;
$a1->magic();
$b1->set(1);
echo "{$a1->n} = {$b1->n}\n";

// Outputs 0 = 1 (magic() method is called a little earlier)
$a2 = new demo();
$a2->magic();
$b2 = clone $a2;
$b2->set(1);
echo "{$a2->n} = {$b2->n}\n";

Expected result:
----------------
1 = 1
1 = 1

Actual result:
--------------
1 = 1
0 = 1