Bug #25918
closed500 ISE on fetching task during capsule sync
Description
a 3.11 pipeline syncing a capsule threw an 500 with:
```
500 Internal Server Error: <h1>Server Error (500)</h1>
2019-01-24T17:33:57 [E|bac|] Error in progress calculation
2019-01-24T17:33:57 [E|bac|] undefined method `all?' for nil:NilClass (NoMethodError)
/opt/theforeman/tfm/root/usr/share/gems/gems/katello-3.11.0.rc2/app/lib/actions/pulp/abstract_async_task.rb:69:in `done?'
/opt/theforeman/tfm/root/usr/share/gems/gems/katello-3.11.0.rc2/app/lib/actions/pulp/consumer/sync_capsule.rb:22:in `run_progress'
/opt/theforeman/tfm/root/usr/share/gems/gems/dynflow-1.2.0/lib/dynflow/action/progress.rb:17:in `block in run'
/opt/theforeman/tfm/root/usr/share/gems/gems/dynflow-1.2.0/lib/dynflow/action/progress.rb:33:in `ensure in with_progress_calculation'
/opt/theforeman/tfm/root/usr/share/gems/gems/dynflow-1.2.0/lib/dynflow/action/progress.rb:32:in `with_progress_calculation'
/opt/theforeman/tfm/root/usr/share/gems/gems/dynflow-1.2.0/lib/dynflow/action/progress.rb:16:in `run'
```
This may be some sort of race condition