title: Setting Celery Task attributes (i.e time_limit and soft_time_limit) does not work
body: <p>According to this thread, the problem is resolved but seems like it is not .
  <a href="https://stackoverflow.com/questions/11672179/setting-time-limit-on-specific-task-with-celery">Setting Time Limit on specific task with celery</a></p>
  
  <p>My current Celery version is 3.1.18 (Cipater).</p>
  
  <p>I am trying overwrite default settings of a Task. Objective is to change the softtimelimit and hard time limit of the task because the same task is being used for multiple purposes.</p>
  
  <p>Passing soft_time_limit and time_limit to MyTask constructor to change default settings.</p>
  
  <pre><code>///celery/app/ task.py
  class MyTask(task.Task):   
      time_limit = 100
      soft_time_limit = 110
      max_retries = 0
  
  def __init__(self, time_limit=None, soft_time_limit=None,
               max_retries=None, *args, **kwargs):
      if time_limit:
          self.time_limit = time_limit
      if soft_time_limit:
         self.soft_time_limit = soft_time_limit
      if max_retries:
         self.max_retries = max_retries
      task.Task.__init__(self, *args, **kwargs)
  
  
  t1 = MyTask(time_limit=30, soft_time_limit=20,
          max_retries=5)
  or
  
  t1 = MyTask()
  t1.time_limit = 30
  t1.soft_time_limit = 20
  </code></pre>
  
  <p>Then pass the t1.si() to task.RetryableChain(...)</p>
  
  <pre><code>job = task.RetryableChain(...)
  job.delay()
  </code></pre>
  
  <p>When the run method is being called by worker, it still receives the old value (time_limit = 100) where as I have set time_limit = 30.</p>
  
  <p>Please let me know if the issue is still exist in 3.1.18 version.</p>