Use manual debugger-in-use flag in nursery and spawn task

tractor/_spawn.py

@@ -366,7 +366,9 @@ async def new_proc(
                                 await proc.wait()
 
                     if is_root_process():
-                        await maybe_wait_for_debugger()
+                        await maybe_wait_for_debugger(
+                            child_in_debug=_runtime_vars.get('_debug_mode', False),
+                        )
 
                     if proc.poll() is None:
                         log.cancel(f"Attempting to hard kill {proc}")

tractor/_supervise.py

@@ -50,6 +50,7 @@ class ActorNursery:
         self._cancel_after_result_on_exit: set = set()
         self.cancelled: bool = False
         self._join_procs = trio.Event()
+        self._at_least_one_child_in_debug: bool = False
         self.errors = errors
         self.exited = trio.Event()
 
@@ -64,6 +65,11 @@ class ActorNursery:
         nursery: trio.Nursery = None,
         debug_mode: Optional[bool] = None,
     ) -> Portal:
+        '''
+        Start a (daemon) actor: an process that has no designated
+        "main task" besides the runtime.
+
+        '''
         loglevel = loglevel or self._actor.loglevel or get_loglevel()
 
         # configure and pass runtime state
@@ -73,6 +79,7 @@ class ActorNursery:
         # allow setting debug policy per actor
         if debug_mode is not None:
             _rtv['_debug_mode'] = debug_mode
+            self._at_least_one_child_in_debug = True
 
         enable_modules = enable_modules or []
 
@@ -287,7 +294,9 @@ async def _open_and_supervise_one_cancels_all_nursery(
                     # will make the pdb repl unusable.
                     # Instead try to wait for pdb to be released before
                     # tearing down.
-                    await maybe_wait_for_debugger()
+                    await maybe_wait_for_debugger(
+                        child_in_debug=anursery._at_least_one_child_in_debug
+                    )
 
                     # if the caller's scope errored then we activate our
                     # one-cancels-all supervisor strategy (don't
@@ -341,6 +350,9 @@ async def _open_and_supervise_one_cancels_all_nursery(
 
         ) as err:
 
+            await maybe_wait_for_debugger(
+                child_in_debug=anursery._at_least_one_child_in_debug
+            )
             # If actor-local error was raised while waiting on
             # ".run_in_actor()" actors then we also want to cancel all
             # remaining sub-actors (due to our lone strategy: