46.4. Every municipality which, as a result of an annexation, is situated in part in two regional county municipalities, shall form part as a whole, from the annexation, of the regional county municipality in which it was situated before the annexation. However, the adjudication for unpaid taxes of immovables situated in a territory governed by the Municipal Code (chapter C-27.1) before the annexation and any proceeding for the redemption of such immovables shall be carried out by the secretary-treasurer of the regional county municipality which effected the sale.