Performing a task that errors prior to a yield calls onerror twice

[sukima]

Ember twiddle demo

It seems that if a task errors prior to a yield statement it has the unfortunate result of calling Ember.onerror twice instead of once.

theTask: task(function* () {
  throw new Error('bork');
}).drop()

<button {{action (perform this.theTask)}}>Go</button>

Pressing the button once will call Ember.onerror twice.

Calling this.theTask.perform() will also call Ember.onerror twice.

[maxfierke]

I think this might be the same issue as https://github.com/machty/ember-concurrency/issues/216?