from2 doesn't work without through2

[tamtakoe]

I try it and get infinite loop in headStream

var headStream = from2.obj(function (size, next) {
    var file = new File({
        path: 'head.js',
        contents: new Buffer('head content')
    });
    next(null, file);
})

series(headStream, otherStream)
    .pipe(g.concat(name))
    .pipe(gulp.dest(destPath))

I try it and get 16 loops (size = 16), but head file doesn't write to output file

var flag = false;
var headStream = from2.obj(function (size, next) {
    if (flag) return this.push(null);
    ...
    flag = true;
    next(null, file);
})
...

If I use through it works!

var headStream = from2.obj(function (size, next) {
    ...
    this.push(file)
    next();
})
.pipe(through2.obj(function (file, enc, callback) {
    callback(null, file);
}));
...

Why? And how to do it without through?

[mafintosh]

could you provide a simple runnable test case that doesn't use gulp to showcase this error? then it might be easier to pinpoint what is wrong :)