When a model contains a field translatable which has a unique
constrain, it is impossible to copy a record. Indeed, the unicity
constrain is always triggered, even if the model takes in charge the
overriding of the copy method to avoid duplication.
Introduced with commit ce7f31b0b0, with the goal to target only
XML/HTML translations. We apply this behavior in case of a callable
translate property, to target only the desired problematic use case.
opw-749481
Nicolas Martinelli