getOrderedView() cached, child updates not seen

Using the built-in object DB, the results of getOrderedView seem to get 
cached such that if I update a child and change the property on which 
I'm ordering subsequent calls to getOrderedView return the same as 
before the update. It *does* update correctly when a new child is 
attached, however.

It turns out that calling .invalidate() on the collection nukes the 
cached view, too, so getOrderedView works again. Is this correct 
behavior, such that I should call this._parent.invalidate() in any code 
that updates an object, or is it a bug?

-Joshua