For new instances, we must set also the attribute with value `None` as they may
be tested later.
Closes#15060
(grafted from bfe3756af384f4fce94244761d5f5dd3f62d0ff6)
--HG--
branch : 7.0
This avoid to clear the sale if there are no actual change on the sale order.
Closes#14171
(grafted from 51e9c921e4e44a90472eebcfa137170e2ee28ec0)
--HG--
branch : 7.0