[1.6.x] Fixed #22710 -- Documented aggregation behavior for empty QuerySets.
[1.6.x] Fixed #22710 -- Documented aggregation behavior for empty QuerySets.

Thanks matklad for the report.

Backport of 7c6e96ec1f from master

django-nonrel/django,felixjimenez/django,felixjimenez/django,django-nonrel/django,redhat-openstack/django,redhat-openstack/django,felixjimenez/django,django-nonrel/django,django-nonrel/django,redhat-openstack/django,redhat-openstack/django,felixjimenez/django