message in queue impact by another message

[liu11hao11]

1.I send a message to my queue,I called this message “A”,In my code ,"A" is not unacked, and then I requeue "A",handle "A" takes a lot time.
2.in the same time,another Message "B" comes, and acked.
3.then I receive the requeue meassge ,but "B" appear in my console.not "A"

I was so confused,
my code goes here:

const createContext = require('rabbit.js').createContext;

var context = createContext(config.QUEUE_LOCATION);

context.on('ready', () => {

    var sub = context.socket('WORKER', { prefetch: 1 });
    sub.setEncoding('utf8');
    sub.on('data', (message) => {

        handle(sub,message)
    });
    const cpus = require('os').cpus();
    async.forEachOf(cpus, (value, i, cb) => {
        sub.connect(config.QUEUE_NAME, function () {
            console.log(i, 'connected');
            cb();
        });
    }, (err) => {
        if (err)
            console.log(new Error(err), 'rabbitmq sub.connect error');
    });
});
async function handle(sub,message){
    console.log('received:', message);
    var msg = {};
    const TAG = "handle-msg";
    console.time(TAG);
    message=JSON.parse(message)
    if (message.test) {
        console.log("ack")
        sub.ack();
        return;
    }
    console.log('requeue');
    await sleep(10000);
    sub.requeue();
    return;

}
function sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms))
}