Comment 0 for bug 309091

  Closing a stream opened with :IF-EXISTS :SUPERSEDE with :ABORT T leaves no
  file on disk, even if one existed before opening.

  The illegality of this is not crystal clear, as the ANSI dictionary
  entry for CLOSE says that when :ABORT is T superseded files are not
  superseded (ie. the original should be restored), whereas the OPEN
  entry says about :IF-EXISTS :SUPERSEDE "If possible, the
  implementation should not destroy the old file until the new stream
  is closed." -- implying that even though undesirable, early deletion
  is legal. Restoring the original would none the less be the polite
  thing to do.