Cal. Pub. Contract Code § 20436
If an action is commenced under the provisions of this chapter to determine the validity of any contract or proposed contract, and the contract has not been signed, the contractor shall not be obligated to sign the same until a judgment sustaining the validity of the proceedings and the proposed contract has become final. If the contractor has signed and executed the contract, he shall not be obligated to begin work until a judgment sustaining the validity of the proceedings and the contract has become final. If a judgment is entered holding the contract invalid, the contractor shall be discharged and relieved of all obligation under the contract, and he and his sureties shall be discharged and relieved of all obligation upon any bond required by law in connection with such contract.
Ca. Pub. Cont. Code § 20436