akka/akka — pull request #644 by rkuhn (2012-08-21 11:47:22+00:00)
Title: add NullMessage after Supervise to prevent race, see #2418

- parent just checked for system messages and finds none
- Supervise is enqueued to parent
- Failed is enqueued to the parent
- Failed is processed before Supervise and thus dropped due to
non-matching UID

remedy is to enqueue NullMessage after enqueuing Supervise but before
really starting the actor, so that if NullMessage overtakes Supervise
the loop in processMailbox will then pick up Supervise next