Data from streams are not merged

[unlight]

Consider this example:

/// <reference path="../typings/tape/tape.d.ts" />
/// <reference path="../typings/node/node.d.ts" />
var test = require("tape");
var merge2 = require('merge2');
var inherits = require("util").inherits;

var Readable = require("stream").Readable;
inherits(CharsStream, Readable);

function CharsStream(options) {
    Readable.call(this);
    this.timeout = options.timeout || 100;
    this.count = options.count || 1;
}

CharsStream.prototype._read = (function () {
    var c = "a".charCodeAt(0);
    return function () {
        var letter = String.fromCharCode(c++);
        var isEnd = (c > "d".charCodeAt(0));
        if (isEnd) {
            this.push(null);
            return;
        }
        var self = this;
        setTimeout(function () {
            var o = new Array(~~self.count + 1).join(letter);
            self.push(o);
        }, ~~(Math.random() * self.timeout));
    };
})();

test("merge streams", function (t) {
    var s1 = new CharsStream({count: 1});
    var s2 = new CharsStream({count: 2});
    var s = merge2([s1, s2]);
    s.on("data", function (chunk) {
        console.log(chunk.toString());
    });
    s.on("end", t.end);
})

Run: Results:

bb
cc
a

Where are other values: aa, b, c?

Next run:

a
bb
c

Where are other values: aa, b, cc?

Is it expected behavior?

[zensh]

CharsStream.prototype._read is wrong, you can not push chunk to ended stream, you should remove setTimeout

[unlight]

Thanks for help. Timeout was added to emulate async process.