Scheduler: Can't localize the heap, as the .clear() method will set it to a new

list. (Why isn't there a list.clear()?)

celery/worker/scheduler.py

@@ -38,38 +38,37 @@ class Scheduler(object):
         """The iterator yields the time to sleep for between runs."""
 
         # localize variable access
-        heap = self._queue
         nowfun = time.time
         pop = heapq.heappop
         ready_queue = self.ready_queue
 
         while 1:
-            if heap:
-                eta, priority, item, callback = verify = heap[0]
+            if self._queue:
+                eta, priority, item, callback = verify = self._queue[0]
                 now = nowfun()
 
                 # FIXME: Need a generic hook for this
                 if item.task_id in revoked:
-                    event = pop(heap)
+                    event = pop(self._queue)
                     if event is verify:
                         item.on_ack()
                         self.logger.warn(
                                 "Mediator: Skipping revoked task: %s[%s]" % (
                                     item.task_name, item.task_id))
                     else:
-                        heapq.heappush(heap, event)
+                        heapq.heappush(self._queue, event)
 
                 if now < eta:
                     yield min(eta - now, self.max_interval)
                 else:
-                    event = pop(heap)
+                    event = pop(self._queue)
 
                     if event is verify:
                         ready_queue.put(item)
                         callback and callback()
                         yield 0
                     else:
-                        heapq.heappush(heap, event)
+                        heapq.heappush(self._queue, event)
             yield None
 
     def empty(self):