How are js files merged?

I'm making a small change to one js file. In development mode everything is fine. However, when I push it to the server, even if a file is changed, the merged files are still getting the same name.

So even after a file is changed there production server is still serving:

```

```

So people have to clear their cache to get the new update, which is hard to explain...

In `production.coffee` I have:

```
app.enable 'merge javascripts'
```

Is there a way to less aggressively cache? Or a way to make it change the file name on every push?