Section 69. If a default is entered under section sixty-seven, or if redemption is not made within the time and upon the terms fixed by the court under the preceding section, or if at the time fixed for the hearing the person claiming the right to redeem does not appear to urge his claim, or if upon hearing the court determines that the facts shown do not entitle him to redeem, a decree shall be entered which shall forever bar all rights of redemption. If no innocent purchaser for value has acquired an interest, such decree may be vacated in the discretion of the court upon petition filed by the petitioner at any time.