Test explicitly the amount on each line instead of simply comparing to the quantity.
Jérome Perrin authored
Test for source were wrong, in the case of source, quantity is not the same sign as for destination.



git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@28301 20353a03-c40f-0410-a6d1-a30d3c3de9de
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