fix: bug when creating CE from LR

if no consignee was set on the LR (possible if LR is Cost Estimate only)
then creating the CE would crash because we were wrongly using the consignee as
partner when playing the sale.order onchanges
I know that you know, but are you sure you don't want to import `nose.tools` assertions? I doubt it gets more little :cat: killed. (not blocking over that)