Description:
------------
I'm trying code on PHP commit 51c90e999fabda0cc10b82e0617e6e45797bf81d. With the latest I get SIGSEGV.

Following code works with PHP 5.0.0 - 5.6.1 (http://3v4l.org/Lc1QW). Workaround in method Bar::modify():

$this->prop = $this->prop . 'xxx';

Test script:
---------------
class Foo
{
    private $var;

    public function buggy()
    {
        $bar = new Bar;
        $bar->prop = & $this->var;
        $bar->modify();

        var_dump($this->var);
    }
}

class Bar
{
    public $prop;

    public function modify()
    {
        $this->prop .= 'xxx';
    }
}

$o = new Foo;
$o->buggy();


Expected result:
----------------
string(3) "xxx"

Actual result:
--------------
NULL