Description:
------------
PHP 5.05 modifies the handling of isset($this->$x) when $x is not set.

This breaks many existing scripts, and is not properly documented IMHO.

Reproduce code:
---------------
<?php
        class A {
                function A() {
                        $x='';
                        var_dump(isset($this->$x));
                        }
        }

        new A();
?>

With php 5.05 :
Fatal error: Cannot access empty property in /home/sysop/test.php on line 5

With php 5.04:
bool(false)