tractor/nooz/248.misc.rst

Adjust the tractor._spawn.soft_wait() strategy to avoid sending an actor cancel request (via Portal.cancel_actor()) if either the child process is detected as having terminated or the IPC channel is detected to be closed.

This ensures (even) more deterministic inter-actor cancellation by avoiding the timeout condition where possible when a whild never sucessfully spawned, crashed, or became un-contactable over IPC.