Make testLegacyReturnedSalePackingList a virtual copy of testReturnedSalePackingList

As long as there is very few differences between testReturnedSalePackingList
and testLegacyReturnedSalePackingList, it is more maintainable not to copy and
paste everything.

If a future change in testReturnedSalePackingList breaks
testLegacyReturnedSalePackingList, then we'll reconsider duplicating the whole
file.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@41552 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/tests/testReturnedSalePackingList.py

@@ -33,7 +33,7 @@ from Products.ERP5Type.tests.ERP5TypeTestCase import ERP5TypeTestCase
 from zLOG import LOG
 from AccessControl.SecurityManagement import newSecurityManager
 from Products.ERP5Type.tests.Sequence import SequenceList
-from testPackingList import TestPackingListMixin
+from Products.ERP5.tests.testPackingList import TestPackingListMixin
 from DateTime import DateTime
 from Products.ERP5Type.Errors import UnsupportedWorkflowMethod 
 from Products.ERP5.tests.utils import newSimulationExpectedFailure