When a container died before we got into the allocation code (inside
the allocator run loop) we would not cancel the allocation since the
container death event will have been processed by the allocator before
it had any knowledge of the container.
The fix is to move the container-aliveness check inside the allocation
code. That way we still detect the death even if the event has already
flown past.
We only need to perform the check once, since any subsequent death
will result in an event that is processed by the allocator when it has
recorded the container in its state.
Fixes#1459.
Matthias Radestock
751ccd02f6