Fix infinite loop when setting internal_quantity

There could be difference for Float field between the written value and the
read one. This could lead to an infinite loop of write calls, so we also test
that it is not already writing the same internal value.

issue3332
review1109002
(transplanted from 43b8d3d42033fb6fe5134cee3bc9facb0d351451)

move.py

@@ -534,7 +534,8 @@ class Move(Workflow, ModelSQL, ModelView):
         for move in moves:
             internal_quantity = cls._get_internal_quantity(move.quantity,
                     move.uom, move.product)
-            if internal_quantity != move.internal_quantity:
+            if (internal_quantity != move.internal_quantity
+                    and internal_quantity != vals.get('internal_quantity')):
                 cls.write([move], {
                         'internal_quantity': internal_quantity,
                         })