why return false in action could not render views in 2.0 and it will in 1.3.4

phalcon version 1.3.4

public function loginAction()
{
    if(!$this->request->isPost()) return false;   // it will render login.phtml
}

phalcon version 2.0

public function loginAction()
{
    if(!$this->request->isPost()) return false;   // it could not render login.phtml , when i use return true ,it can
}

why????