Otherwise doesn't forward 'end' event

In the below snippet, I expect both the generator and otherwise 'end' events to fire, but only the generator's ever does.

``` js
var generator = $(function (push, next) {
push(null, $.nil);
});

generator.on('end', function () {
console.log('generator end');
})

var otherwise = $([]).otherwise(generator).on('end', function() {
console.log('otherwise end')
});
generator.resume();
otherwise.resume();
```