Cross namespace tick handler doesn't work as I'd hope...

main.php

<?php
include('TickThing.class.php');

echo "Do something\n";
sleep(30);
echo "Do something else\n";

Output

#php main.php
Registering tick function as Tick\Thing::tick()
* Tick
* Tick
Do something
Do something else

TickThing.class.php

<?php namespace Tick;
declare(ticks=1);

class Thing {
    static public function init() {
    	echo "Registering tick function as " . self::CLASS . "::tick()\n";
        register_tick_function([self::CLASS, 'tick']);
    }

    static public function tick() {
	echo "* Tick\n";
    }
}

Thing::init();