Delete a parent don't stop the children workers

```
What steps will reproduce the problem?
1.Create a parent job with children
2.Delete the parent


What is the expected output? What do you see instead?
The workers should stop working on the children jobs.
They don't.

Please use labels and text to provide additional information.


```

Original issue reported on code.google.com by `corvaz...@gmail.com` on 1 Oct 2010 at 2:16
