message: Don't explicity disable keepalive
  We want to use the OS default normally
diff: @@ -186,7 +186,9 @@ fn open_socket(params: &ConnectParams) -> Result<Socket> {
  SocketAddr::V6(_) => Domain::ipv6(),
  };
  let socket = Socket::new(domain, Type::stream(), None)?;
  - socket.set_keepalive(params.keepalive())?;
  + if let Some(keepalive) = params.keepalive() {
  + socket.set_keepalive(Some(keepalive))?;
  + }
  let addr = SockAddr::from(addr);
  let r = match params.connect_timeout() {
  Some(timeout) => socket.connect_timeout(&addr, timeout),
  