KeyError occurs when we receivea job handle that is not in handle_to_request_map when the client is executing recv_* commands

[paiweilai]

KeyError occurs when we receive a job handle that is not in self.handle_to_request_map
A possible reason is that the client timeout before it receives a JOB_CREATED when submitting a job.
In this case, the request is no registered in the handle_to_request_map.`
At some point later when the client receives a command that tries to access the map by an unknown job_handle,
KeyError is raised. Need more investigation to find the actual reason.