title: Task stops retrying after random number of tries
body: <p>As the subject says, tasks that used to retry until they reach defined "max_retries" count, now sometimes stop doing that after random number of times :/. Sometimes they stop retrying after couple hundred times, sometimes after just few times.</p>
  
  <p>What I noticed is that if I restart "celery beat" process - after some minutes, some tasks, that "were quite" for hours, start retrying again as they should.</p>
  
  <p>Can't pinpoint precisely when it started happening, but it might be after upgrade of Celery, RabbitMQ or Django.</p>
  
  <p>Anybody have an idea why this is happening ?</p>
  
  <p>I'm running:</p>
  
  <pre><code>Django: 1.7.3
  RabbitMQ: 3.4.2
  celery:3.1.17
  kombu:3.0.24
  billiard:3.3.0.19
  python:2.7.3
  py-amqp:1.4.6
  </code></pre>
  
  <p>Celery settings:</p>
  
  <pre><code>CELERY_ACKS_LATE            = True
  CELERY_SEND_EVENTS          = True
  CELERY_TRACK_STARTED        = True
  CELERY_DISABLE_RATE_LIMITS  = True
  CELERYD_PREFETCH_MULTIPLIER = 1
  CELERY_SEND_TASK_SENT_EVENT = True
  </code></pre>
  
  <p>Task code looks smth. like this:</p>
  
  <pre><code>class ABCTask(AbortableTask):
      ignore_result = False
      max_retries = 288*5
  
      def run(self):
          try:
              [...]
          except NoAvailableDevices as e:
              try:
                  self.retry(exc=e)
              except MaxRetriesExceededError, e:
                  [...]
  </code></pre>
  
  <p>Thanks,
  Lauris </p>