When real property or any income or interest in the real property or income has been transferred within the meaning of subsection (c) of section 2107 and the transferee has sold, mortgaged or leased the property or any income or interest in the property, the interest of a bona fide purchaser, mortgagee or lessee in the property shall not be subject to any lien for the taxes imposed by this article.
72 P.S. § 9172