When event on which contract is contingent to be deemed impossible, if it is the future conduct of a living person

When event on which contract is contingent to be deemed impossible, if it is the future conduct of a living person.—If the future event on which a contract is contingent is the way in which a person will act at an unspecified time, the events shall be considered to become impossible when such person does anything which renders it impossible that he should so act within any definite time, or otherwise than under further contingencies.