Description:
------------
See test script. An autoload function was added to autoload queue in another autoload function. But the "child" autoload function was not called after other functions.
It works on 5.5 and 5.6.

Test script:
---------------
<?php
spl_autoload_register(function($name){
    if($name == 'C') {
        spl_autoload_register(function($name){
            if($name == 'C') {
                class C {
                    function __construct(){
                        echo "I'm C.\n";
                    }
                }
            }
        });
    }
});

$c = new C();


Expected result:
----------------
I'm C.

Actual result:
--------------
PHP Fatal error:  Uncaught Error: Class 'C' not found