All our tryjobs try to deapply a patch when they run now, due to erik chen's work on this. 

https://chromium-swarm.appspot.com/task?id=404e72316c258f10&refresh=10 is an example of this.

It hits an assertion error, because it tries to deapply a patch, but the led job doesn't have a patch applied.

Not sure exactly if this is something we could really fix? It looks like the tryjob really should have failed, it just looks confusing to a user why it failed probably.