If the person or corporation applying to the city council for any such permit shall have a valid and existing franchise or permission for the structure desired, under any valid ordinance of the city, it shall be the duty of said council to grant such permit; provided, that said council shall defer, or temporarily refuse the granting thereof, until such time as it deems proper in its discretion in all cases where the street or alley, or other public place on which the work is desired to be done, is occupied or about to be occupied in any work by the city in improving or repairing such street, alley or public place, or in repairing, extending or constructing water mains, sewer pipe or other property of the city; or in cases where such street, alley or public place is occupied or is about to be occupied by any other person or corporation having a right to use the same in such manner as to render it seriously inconvenient to the public to permit any further obstruction thereof at said time; and provided further, that said council shall, in granting said permits, so regulate or defer the granting thereof that a sufficient portion of such street, alley or public place shall, as far as possible, be open for public use for purposes of traffic, and in all cases any work of the city or its contractors or employees shall have precedence over all other work of every kind. (Prior code § 4.52.020.)