oca-purchase/odoo-bringout-oca-purchase-workflow-purchase_stock_packaging/purchase_stock_packaging/readme/USAGE.rst

* For instance, create a sale order with a route that trigger make to order stock rules (and a purchase order).
* On that sale order, force using a product packaging that would not be the
  default one for the filled in qunatity.
* The purchase order line created should use the same product packaging.