McDougal Contractors made a contract with Rekowski to build an apartment house for a specific price. A number of serious apartment house fires broke out in the city, and an ordinance was adopted by the city council increasing the fire precautions that had to be taken in the construction of a new building. Compliance with these new requirements would make the construction of the apartment house for Rekowski more expensive than McDougal had originally contemplated. Is McDougal discharged from the contract to build the apartment house?