title: Howto use celery.set() method to update properties of abstract base class
body: <p>I want to use the celery.signature().set() method to change the configuration of my task when calling it in a chain. </p>
  
  <p>Here's what my task looks like</p>
  
  <pre><code>class MyBaseTask(Task)
    myconfig = None
  
  
  @app.task(base=MyBaseTask)
  def mytask():
    print mytask.myconfig
  </code></pre>
  
  <p>Here's how I would expect to call the chain</p>
  
  <pre><code>chain(mytask.s(message).set(myconfig=config1), mytask.s().set(myconfig=config2))
  </code></pre>
  
  <p>is this possible? Other task related config can be set like this, queue for instance. How can I expose this behavior in my abstract base class? </p>