What steps will reproduce the problem?
Make a set with empty slots only!
Equip items
Tell CG to equip the 'naked' set

What is the expected output? What do you see instead?
CG should unequip the items

What version of the product are you using?
r579 (latest)

Tracked it down
The problem is in ClosetGnome:IsSetFullyEquipped, more so in the line:
--------------------
        if slot > 0 and item and not IsEquippedItem(item) then
            return false
        end
--------------------
The problem is, item is false for empty slots and nil for slots not active in the set, so this if will always return false for 'naked sets' and CG thinks the set is already fully equiped by the char
--------------------
        if slot > 0 and (item or item == false) and not IsEquippedItem(item) then
            return false
        end
--------------------
item is nil for inactive slots which evaluates to false, but item is false for empty slots, thats the problem, with this change CG unequips empty slots as expected.