Pulp

Description of problem:

When an RQ restarts (or dies) the tasks assigned to that worker get marked as cancelled. The cancelled state is correct, but users who dispatch work don't expect random cancelling of tasks so this isn't a great behavior.

To reproduce:
1. Start Pulp system with exactly 1 worker
2. Start a really long sync
3. List the tasks and observe that the task you submitted is in the running state
4. During the sync `kill -9` the worker
5. Start that worker up again
6. List the tasks again and observe that the task you submitted is in the cancelled state

Expected result: That the work you submitted to Pulp doesn't end up in the cancelled state when a worker dies. I expect it to be re-picked up by the worker and be in the running state.