Don't call a useless getPrice on edit(price=x)

Base.edit has this feature of not actually modifying the properties when
the new property value is same as the current one, so when we do
`movement.edit(price=x)`, this will cause an implicit getPrice.

As price lookup is a bit slow, do not lookup price in this case.

/cc @vpelletier @kazuhiko @romain 

/reviewed-on nexedi/erp5!259

product/ERP5/Document/Movement.py

@@ -230,8 +230,6 @@ class Movement(XMLObject, Amount, CompositionMixin, AmountGeneratorMixin):
       if self.isMovingItem(item)]
 
   # Pricing methods
-  # _getPrice is defined in the order / delivery
-  # Pricing mehod
   def _getPrice(self, context):
     context = self.asContext(context=context,
                              quantity=self.getConvertedQuantity())
@@ -327,7 +325,7 @@ class Movement(XMLObject, Amount, CompositionMixin, AmountGeneratorMixin):
            DeprecationWarning)
 
     local_price = self._baseGetPrice()
-    if local_price is None:
+    if local_price is None and evaluate:
       # We must find a price for this movement
       local_price = self._getPrice(context=self)
     return local_price

product/ERP5/tests/testSupply.py

@@ -588,6 +588,19 @@ class TestSaleSupply(TestSupplyMixin, SubcontentReindexingWrapper,
     preference.setPreferredPricingOptimise(False)
     self._clearCache()
 
+  def test_getPriceDoesNotLookupPriceDuringEdit(self):
+    """Test getPrice does not lookup price during edit.
+    """
+    movement = self._makeRealMovement()
+
+    def methodThatShouldNotBeCalled(*args, **kw):
+      self.fail("price lookup should not happen")
+    movement.getPriceCalculationOperandDict = methodThatShouldNotBeCalled
+    movement._getPrice = methodThatShouldNotBeCalled
+
+    movement.edit(price=10)
+    self.assertEqual(10, movement.getPrice())
+    self.abort()
 
   def _createTwoHundredSupplyLineInASupply(self):
     supply = self._makeSupply(