Due to a new feature described here angular/angular.js@e46100f, attributes that end with "-start" or "-end" will get that truncated. So auto-start gets passed to the directive as "auto".

Took me quite a bit of time to figure out what was going on (had to git bisect the angular codebase).

The simple solution would be to call the attribute "autostart", but I guess there could be other approaches to this.