Code review comment for lp:~camptocamp/account-financial-tools/account-contraints-state-vre

Does this change allow to change a move from 'posted' to 'unposted' when it should not have been allowed? This constraint does maybe exist elsewhere, if it it does, so your fix seems correct to me. Otherwise, we should check that that the change is unposted→posted and not posted→unposted.