In the case where we have a subordinate charm, libjuju juju status
on the unit returns an empty dictionary, therefore the existing None
check would fail and the subordinate status would never get set.
The result being subordinates not included in the returned Iterator.
Add zaza.openstack.utilities.juju.get_subordinate_units to get a list
of all subordinate units associated with units in unit_list.
Subordinate can be filtered by using 'charm_name' which will only
return subordinate units which have 'charm_name' in the name of the
charm.
Corey Bryant
Chris MacNaughton
Liam Young
Andrew McLeod
Alex Kavanagh
David Ames
Frode Nordahl