Remove record from xxx2many in wizard
Currently when a record is removed from a xxx2many field, it is not really removed if the id >= 0 (see Group.remove).
Indeed it is not really what you could expect from a wizard as nothing is stored but still the xxx2many could be record with real ids.
So the idea is that the test should also see if the parent (if existing) doesn't have a negative id. If yes, then we are in the wizard case (or any other) where it makes no sense to keep displaying the deleted record to the user because the parent is not yet saved.