* Fixes#18900: introduce/raise QuerySetNotOrdered exception
Defines a new exception, `QuerySetNotOrdered`, and raises it in
`OptionalLimitOffsetPagination.paginate_queryset` in the right
conditions:
- the iterable to be paginated is a QuerySet isinstance
- the `queryset.ordered` flag is not truthy
* Don't try to reapply ordering if ordering is already present
* Add ordering for failing tagged-objects list API endpoint
I chose to implement this here for TaggedItemViewSet, rather than on the
model, because any meaningful ordering is going to be done on the
related Tag instance and I didn't want to introduce potential, not well
understood side-effects by applying a model-wide ordering via a related
model field.
* Add default Token ordering behavior
* Adds basic tests for raising QuerySetNotOrdered
* Note why ordering is not applied in TaggedItem.Meta
