rpc: recognize non-graceful shutdown of rpc clients
rpc: recognize non-graceful shutdown of rpc clients

If a rpc client disconnects without proper shutdown, it remains in the list of
connected clients which produces

  WARNING:asyncio:socket.send() raised exception.

each time the rpc tries to send data.

Inspired-by: Zhuofei Wang <9255900528f4511b9c5ed9f6b61476542e77233f@gmail.com>
Signed-off-by: Florian Scherf <01ea296d94b35b47de034b473506bbbc8961ebf2@pengutronix.de>

pengutronix/aiohttp-json-rpc,pengutronix/aiohttp-json-rpc,pengutronix/aiohttp-json-rpc