ZAP auth sometimes not retried using TCP

[jean-airoldie]

Filed this issue in libzmq.

[jean-airoldie]

When using CURVE, the authentication is simply not retried.

Minimal reproduction example:

use libzmq::{prelude::*, auth::*, *};
use std::{time::Duration, convert::TryInto};

#[test]
fn test_issue_30() {
    let ctx = Ctx::new();

    let server_cert = CurveCert::new_unique();
    let client_cert = CurveCert::new_unique();

    let addr: TcpAddr = "127.0.0.1:*".try_into().unwrap();

    let server_creds = CurveServerCreds {
        secret: server_cert.secret().to_owned(),
    };

    let client_creds = CurveClientCreds {
        client: client_cert,
        server: server_cert.public().to_owned(),
    };

    let server = ServerBuilder::new()
        .bind(&addr)
        .mechanism(server_creds)
        .recv_timeout(Duration::from_millis(200))
        .with_ctx(&ctx)
        .unwrap();

    let bound = server.last_endpoint().unwrap().unwrap();

    let client = ClientBuilder::new()
        .mechanism(&client_creds)
        .connect(bound)
        .with_ctx(&ctx)
        .unwrap();

    client.send("").unwrap();
    assert!(server.recv_msg().is_err());

    let channel = AuthClient::with_ctx(&ctx).unwrap();
    channel.add_curve_key(client_creds.client.public()).unwrap();

    server.recv_msg().unwrap();
}

[jean-airoldie]

This is most likely related to #44.