Set this multi-environment's manager as the host manager for
        a manager agent in *addr*

async def set_host_manager(self, addr, timeout=TIMEOUT):
        """Set this multi-environment's manager as the host manager for
        a manager agent in *addr*
        """
        r_manager = await self.env.connect(addr, timeout=timeout)
        return await r_manager.set_host_manager(self.manager.addr)