In Mongoid, #persisted? returns false only for new documents:

def persisted?
  !new_record?
end

But if Mongoid strives to adhere to the ActiveModel API (and it seems to), #persisted? should also return false for documents that have been destroyed. From the changelog of ActiveModel 3.0.0:

> A model is persisted if it's not a new_record? and it was not destroyed?

Which would be:

def persisted?
  !new_record? && !destroyed?
end

I'm posting here instead of submitting a patch because I don't know Mongo well, so I wonder: is this a Mongo thing, or is it a bug?