Problem: order payments didn't seem to be loaded in any particular order,
and OrderUpdater#update_payment_state was relying on payment order to de-
termine payment state.
Strategy: Adapt a version of this method from a future version of Spree.
I tried to select a version where I would have to make the absolute mini-
mum number of changes to get it to work. See comments in code for justif-
ications of the changes that I did make.
