(2) Nothing contained in ORS 357.001 to 357.200, 357.330, 357.360, 357.400 to 357.621, 357.975 and 357.990 shall affect nor change the terms of any library contract executed prior to September 13, 1975. However, by mutual consent, the parties to the contract may amend the contract so as to make it conform to all or any of the provisions of ORS 357.001 to 357.200, 357.330, 357.360, 357.400 to 357.621, 357.975 and 357.990. [Amended by 1975 c.476 §27]