Unique fields should cause a uniqueness warning only when validating

Given are two required fields set up to be unique in combination. When submitting or previewing the node/add form with only one of the fields set, this module evaluates their uniqueness rule and issues a warning. That happens in addition to the usual form validation messages, thus being a redundant check with a false result (because the node would never be stored that way).

I think the proper handling would be to not test for uniqueness, unless all involved form fields validate.