spree/spree — pull request #5048 by jordan-brough (2014-07-24 17:22:15+00:00)
Title: Return item cancellation

Creating a new return item should cancel any other return items with the same inventory unit.
This ensures an inventory unit can only be active in a single RMA at a time.
This allows history to be preserved but still allow new RMAs to be created to replace old ones.