Race condition when restarting proc macro server with responses

[Draggu]

When restarting proc macro server we call db.cancell_all() to make sure that no request will be ended during restart, but we are not handling case when there is a response in same time, this res will be pushed to old client queue so it wont be read but it still emits message to response channel used on main loop. We should send message to connection to stop handling requests before we restart and wait for connection to close.