Tweak code comment.

cylc/flow/scheduler.py

@@ -876,8 +876,12 @@ def _load_task_run_times(self, row_idx, row):
             return
 
     def process_queued_task_messages(self) -> None:
-        """Handle incoming task messages for each task proxy."""
+        """Process incoming task messages for each task proxy.
+
+        """
         messages: 'Dict[str, List[Tuple[Optional[int], TaskMsg]]]' = {}
+
+        # Retrieve queued messages
         while self.message_queue.qsize():
             try:
                 task_msg = self.message_queue.get(block=False)
@@ -893,9 +897,8 @@ def process_queued_task_messages(self) -> None:
             messages[task_id].append(
                 (job, task_msg)
             )
-        # Note on to_poll_tasks: If an incoming message is going to cause a
-        # reverse change to task state, it is desirable to confirm this by
-        # polling.
+
+        # Poll tasks for which messages caused a backward state change.
         to_poll_tasks = []
         for itask in self.pool.get_tasks():
             message_items = messages.get(itask.identity)
@@ -913,8 +916,10 @@ def process_queued_task_messages(self) -> None:
                 to_poll_tasks.append(itask)
         if to_poll_tasks:
             self.task_job_mgr.poll_task_jobs(self.workflow, to_poll_tasks)
-        # Remaining messages don't have a receiving task in the pool.
-        # E.g., after manually setting a running task to finished.
+
+        # Remaining unprocessed messages have no corresponding task proxy.
+        # For example, if I manually set a running task to succeeded, the
+        # proxy can be removed, but the orphaned job still sends messages.
         for _id, tms in messages.items():
             warn = "Undeliverable task messages received and ignored:"
             for _, msg in tms: