Any material alteration of a negotiable instrument renders the same void as against anyone who is a party thereto at the time of making such alteration and does not consent thereto, unless it was made in order to carry out the common intention of the original parties;

Alteration by indorsee.-- And any such alteration, if made by an indorsee, discharges his indorser from all liability to him in respect of the consideration thereof.

The provisions of this section are subject to those of sections 20, 49, 86 and 125.