EventEmitter.listeners() returns different results in case longlohn is used

[Flarna]

For events registered via once() the listener() API returns different result if longjohn is used or not.

Reproducer:

var assert = require('assert');
var EventEmitter = require('events').EventEmitter;

function onListener() {}
function onceListener() {}

function test() {
    var eventEmitter = new EventEmitter();

    eventEmitter.on('TheEvent', onListener);
    eventEmitter.once('TheEvent', onceListener);

    var listeners = eventEmitter.listeners('TheEvent');
    assert.equal(listeners[0], onListener);
    assert.equal(listeners[1].listener, onceListener);
    // the following assert passes for longlohn case
    //assert.equal(listeners[1], onceListener); 
}

test();

require('longjohn');

test();

Looks like the longlohn implementation unwraps one level too much in listen() for once listeners.