Lease, sale or mortgage of real estate under power in will or under subsection (i) of Section 28-8.) The provisions of this Article for the lease, sale or mortgage of real estate or interest therein do not apply to leases, sales or mortgages made without order of court by a representative under a power given in the will or under subsection (i) of Section 28-8, but before making a sale or mortgage of real estate it is the duty of the representative to comply with the provisions of Section 12-9. If a contract of the decedent to convey or lease real estate or interest therein requires the giving of warranties, the instrument given by the representative in fulfillment of the contract shall contain the warranties required and they bind the estate as though made by the decedent but do not bind the representative personally. If a representative leases, sells or mortgages a decedent’s real estate or interest, the lease, sale or mortgage is valid regardless of the subsequent setting aside of the will or any other action which might limit or restrain the right of the representative to lease or to convey title or to mortgage the real estate or interest. A lessee, purchaser or mortgagee from a representative obtains the same title or interest as though the instrument were executed by the decedent immediately prior to his death, and the rights and claims of all parties claiming under or through the decedent thereupon are transferred to the consideration received or to be received from such lease, sale or mortgage.