by the United States government

“ A good faith purchaser without knowledge of the commencement of the case and for less than present fair equivalent value has a lien on the property transferred to the extent of any present value given, unless a copy or notice of the petition was so filed before such transfer was so perfected. (d) An action or proceeding under this section may not be commenced after the earlier of— (1) two years after the date of the transfer sought to be avoided ”