Decree affirmed. This litigation comes before this court for the third time. The first phase involved a bill in equity (brought by the present appellants) by way of appeal from a decision of the board of appeals of Canton granting a variance to Robert A. Falls and his wife to enable them to build a two family house on a parcel of land owned by them. In 345 Mass. 117, we held that the decision of the judge upholding the granting of the variance was erroneous. Instead, however, of annulling the decision of the board, we reversed the decree and ordered the ease “to stand for further hearing in conformity with . . . [the] opinion.” Thereafter, on March 18, 1963, the town adopted an amendment to its zoning by-law. Under the amendment, the Falls’ land was placed in a less restrictive zone in which two family houses were permitted and there was no longer any need for a variance. The amendment was challenged in mandamus proceedings by the present appellants on the ground that it constituted spot zoning; it was held to be valid in Sullivan v. Selectmen of Canton, 346 Mass. 784. Thereafter, by a proposed amendment to their original bill in equity, the appellants sought to have the building permit issued to the Falls to build a two *794family house on the locus declared null and void. This motion was denied and a decree was entered in that case dismissing the bill because the subject matter of it had become moot by reason of a valid amendment to the zoning by-law. The present appeal, which is based on the contention that this decree did not conform to the rescript in 345 Mass. 117 is, for the reason set forth in the decree, palpably without merit.