spree/spree — pull request #4870 by jordan-brough (2014-06-25 19:11:48+00:00)
Title: ensure correct order for payments query in OrderUpdater

".last" without an sort order is not guaranteed to return any particular item, especially in postgres.

"If sorting is not chosen, the rows will be returned in an unspecified order"
http://www.postgresql.org/docs/9.3/interactive/queries-order.html

I couldn't think of a reasonable way to write a spec around this since the sort order is just unspecified.