Description:
------------
If you call an object's method, $x->foo(), and then
call parent:;bar() (or self:;bar() or xyz::abc()),
$this will be defined inside bar() and point to the
original object ($x). But if you use call_user_func()
or call_user_func_array(), $this is not defined.


Reproduce code:
---------------
class foo
{
        function a()
        {
                if (isset($this))
                        var_dump($this);
                else
                        print "\$this not defined.\n";
        }
        function b()
        {
                self::a();
                call_user_func(array('self','a'));
        }
}
$x = new foo;
$x->b();

Expected result:
----------------
object(foo)#1 (0) {
}
object(foo)#1 (0) {
}

Actual result:
--------------
object(foo)#1 (0) {
}
$this not defined.