client: fix canceled vs deadline exceeded double-check logic (#2906)
client: fix canceled vs deadline exceeded double-check logic (#2906)


grpc/grpc-go,menghanl/grpc-go,dfawley/grpc-go,stanley-cheung/grpc-go,dfawley/grpc-go,grpc/grpc-go,menghanl/grpc-go,stanley-cheung/grpc-go