“ The District Court, having held that the Georgia Legislature was malapportioned (Toombs v. Fortson, 205 F.Supp. 248) , enjoined appellants, election officials, 'from placing on the ballot to be used in the General Election to be held on November 3, 1964, or at any subsequent election until the General Assembly is reapportioned in accordance with constitutional standards, the question whether a constitutional amendment purporting to amend the present state constitution by substituting an entirely new constitution therefor shall be adopted.' Appellants challenge that provision on the merits. ”