use getRootDeliveryValue() instead of deprecated getDeliveryValue().

git-svn-id: https://svn.erp5.org/repos/public/erp5/sandbox/amount_generator@37035 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/Movement.py

@@ -538,7 +538,7 @@ class Movement(XMLObject, Amount, CompositionMixin, AmountGeneratorMixin):
     """
       Returns the object explanation of this movement.
     """
-    return self.getDeliveryValue()
+    return self.getRootDeliveryValue()
  
   security.declareProtected( Permissions.AccessContentsInformation,
                              'getExplanationTitle')