Child class of AMQPConnection cannot access its own attributes

gistfile1.aw

<?php
class MockAMQPConnection extends AMQPConnection {
	protected $foo = 'bar';

	public function getFoo() {
		return $this->foo;
	}
}

$mock = new MockAMQPConnection();

// The following line will trigger
// Notice: Undefined property: MockAMQPConnection::$foo
echo $mock->getFoo();