Interest in Contract or Supplies.

   Section 121.   No officer or employee of the city shall have a personal interest, direct or indirect, in any contract with the city or be personally interested, directly or indirectly, in the sale to the city of any supplies, material, service or land, except on behalf of the city as an officer or employee. Any willful violation of this section shall constitute malfeasance in office, and any officer or employee found guilty thereof shall thereby forfeit his office.