Change AirflowTaskTimeout to inherit BaseException

Code that normally catches Exception should not implicitly ignore
interrupts from AirflowTaskTimout.

Fixes apache#35644 apache#35474

airflow/exceptions.py

@@ -79,7 +79,10 @@ class InvalidStatsNameException(AirflowException):
     """Raise when name of the stats is invalid."""
 
 
-class AirflowTaskTimeout(AirflowException):
+# Important to inherit BaseException instead of AirflowException->Exception, since this Exception is used
+# to explicitly interrupt ongoing task. Code that does normal error-handling should not treat
+# such interrupt as an error that can be handled normally. (Compare with KeyboardInterrupt.)
+class AirflowTaskTimeout(BaseException):
     """Raise when the task execution times-out."""
 
 

tests/core/test_core.py

@@ -71,11 +71,18 @@ class InvalidTemplateFieldOperator(BaseOperator):
             op.dry_run()
 
     def test_timeout(self, dag_maker):
+        def sleep_and_catch_other_exceptions():
+            try:
+                sleep(5)
+                # Catching Exception should NOT catch AirflowTaskTimeout
+            except Exception:
+                pass
+
         with dag_maker():
             op = PythonOperator(
                 task_id="test_timeout",
                 execution_timeout=timedelta(seconds=1),
-                python_callable=lambda: sleep(5),
+                python_callable=sleep_and_catch_other_exceptions,
             )
         dag_maker.create_dagrun()
         with pytest.raises(AirflowTaskTimeout):