If two persons have entered into a transaction the result whereof is a setoff, wholly or in part, of debts which they owe one another and the estate of one of them is sequestrated within a period of six months after the taking place of the set-off, or if a person who had a claim against another person (hereinafter in this section referred to as the debtor) has ceded that claim to a third person against whom the debtor had a claim at the time of the cession, with the result that the one claim has been set-off, wholly or in part, against the other, and within a period of one year after the cession the estate of the debtor is sequestrated; then the trustee of the sequestrated estate may in either case abide by the set-off or he may, if the set-off was not effected in the ordinary course of business, with the approval of the Master disregard it and call upon the person concerned to pay to the estate the debt which he would owe it but for the set-off, and thereupon that person shall be obliged to pay that debt and may prove his claim against the estate as if no set-off had taken place: Provided that any set-off shall be effective and binding on the trustee of the insolvent estate if it takes place between an exchange or a market participant as defined in section 35A and any other party in accordance with the rules of such an exchange, or if it takes place under an agreement defined in section 35B.