Updated to latest version, 3.2.0. From CHANGELOG:

Version 3.2.0 - 2014-04-21
* Bug fixes (see mercurial logs for details)
* Add warning for moves without origin
* Allow to define the effective date of shipments
* Prevent changing product type if stock moves exist
* Use new methods to compute quantities in StockMixin._search_quantity()
* Split products_by_location into two methods on Move:
  compute_quantities_query and compute_quantities
* Use origin for inventory moves
* Allow partial assignation on Supplier Shipment Return

(rodent)