When a defendant has demurred to, filed a plea to, or otherwise put in issue, a part of the plaintiff's claim and has left the residue of such claim unanswered, the case shall in no event be discontinued merely because the plaintiff has failed to sign judgment as to the unanswered residue; but the plaintiff may, at any term of court at or after which such demurrer or plea is filed or such part of the plaintiff's claim is otherwise put in issue, before or after trial of the issue as to the part answered, provided the case shall not have been discontinued under some other provision of law, take judgment by nil dicit as to such unanswered residue.