On Logout Success, serviceManager->clear() is not sufficient for clearing '_logout/processed' session variable

[achasseux]

The README documentation suggests to write a LogoutSuccessHandler::onLogoutSuccess() method, and call this line : $this->serviceManager->clear();

It is not sufficient for clearing the '_logout/processed' session variable. I have added the line : $request->getSession()->remove(LogoutManager::SERVICE_SESSION_NS);

Without this clearing, if the user wants to login on Consumer1 again and logout again, he will not be logged-out on Consumer2.