[project @ 2003-07-18 14:39:05 by simonmar]
When doing update-in-place, there is a (small) chance that the thunk may have been blackholed and another thread might be waiting on it. We can't therefore just splat it with the value; we have to check whether it is a blocking queue and awaken any threads that might be waiting on it if so. Should fix the scavenge_mutable_list crash reported recently. If it does, it will be merged to STABLE.