move ShutDownImminentException into exceptions.py

rq/exceptions.py

@@ -19,3 +19,9 @@ class UnpickleError(Exception):
 
 class DequeueTimeout(Exception):
     pass
+
+
+class ShutDownImminentException(Exception):
+    def __init__(self, msg, extra_info):
+        self.extra_info = extra_info
+        super(ShutDownImminentException, self).__init__(msg)

rq/worker.py

@@ -18,7 +18,7 @@ from rq.compat import as_text, string_types, text_type
 
 from .connections import get_current_connection, push_connection, pop_connection
 from .defaults import DEFAULT_RESULT_TTL, DEFAULT_WORKER_TTL
-from .exceptions import DequeueTimeout
+from .exceptions import DequeueTimeout, ShutDownImminentException
 from .job import Job, JobStatus
 from .logutils import setup_loghandlers
 from .queue import Queue, get_failed_queue
@@ -722,12 +722,6 @@ class SimpleWorker(Worker):
         return self.perform_job(*args, **kwargs)
 
 
-class ShutDownImminentException(Exception):
-    def __init__(self, msg, extra_info):
-        self.extra_info = extra_info
-        super(ShutDownImminentException, self).__init__(msg)
-
-
 class HerokuWorker(Worker):
     """
     Modified version of rq worker which: