Enrich task return status to register partial completions
The return status of tasks is currently a three-state :
- Exception => the task failed
- True => the task succeeded and did something
- False => the task succeeded and did nothing
We need to extend the return values to allow tasks to return a partial state.
One possible return value could be a dict with multiple values :
- completion: full/partial
- eventful: True/False
- state: variable to pass to the next partial task run
- delay: the delay before reexecution of a partial loading task
Migrated from T536 (view on Phabricator)