title: Celery: Updating name of task to match registered task
body: <p>I changed the name of the directory my celery tasks are in which (judging from the error below) has caused some problems with my future scheduled tasks.</p>
  
  <pre><code>KeyError: 'utils.tasks.foo'
  [2019-02-21 06:25:09,103: ERROR/MainProcess] Received unregistered task of type 'utils.tasks.foo'.
  The message has been ignored and discarded.
  </code></pre>
  
  <p>This task is now registered under <code>services.tasks.foo</code>. I know I have more tasks scheduled and can view the task ids in my Redis broker, however when I look at the scheduled tasks using <code>app.control.inspect().scheduled()</code> only the tasks that have been scheduled since I made the directory change to <code>services.tasks.foo</code> are returned.</p>
  
  <p>Given that Celery isn't recognizing my old tasks, how can I update the task names to match the path that my tasks are now registered under?</p>