Yea, I was thinking the same thing... 

Luckily all the DAS emulations used a very short cycle size, so the candidates would usually still exist (i.e. not yet been removed from _candidates).  Plus, we did keep an eye on the record failure, and it wasn't high, even with churn.

I'm more worried about the live experiment where we had 30 minute cycles, hence this bug must have been more noticeable.  I'll have to check the logs to see the record success rate there.  Though its more difficult to access, as we can't distinguish between failure because of churn or this bug.

Regardless, I'll send her an email.