This is not a bug, but just an illustration of is_callable/call_user_func mess which was fixed in 5.3 comparing to 5.2. The following extended example illustrates inconsistent behaviour of 5.2. Using call_user_func() it passes $this in one case and not in the other, however direct call passes %this in both cases.

<?php
class A {
    public function test() {
        B::foo();
        call_user_func(array("B","foo"));
    }
    public function bar() {
        var_dump($this);
    }
}

class B extends A {
    public function foo() {
        var_dump($this);
    }
    public function test2() {
        A::bar();
        call_user_func(array("A","bar"));
    }
}

$b = new B; $b->test(); $b->test2();
?>

PHP-5.2
-------
object(B)#1 (0) {
}
NULL
object(B)#1 (0) {
}
object(B)#1 (0) {
}

PHP-5.3
-------
object(B)#1 (0) {
}
object(B)#1 (0) {
}
object(B)#1 (0) {
}
object(B)#1 (0) {
}

Ok then, if this is intended, it should probably get mentionned in 5_2->5_3 migration guide, I just added it to the scratchpad and reclassify as documentation problem so it's not forgotten.

No feedback was provided for this bug for over a week, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
the status of the bug back to "Open".