Doubt about license

["Nelson A. de Oliveira" <naoliv@gmail.com>]

Hi mentors!

I am creating a package of a program that have several files with:

* The contents of this file are subject to the Netscape Public
* License Version 1.1 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.mozilla.org/NPL/

Asking the upstream author about the license of the program, he said
that it's legacy code and the program is licensed under GPL only.

My doubt is if it's OK to say on debian/copyright that it's licensed
under GPL, as the author said, or if I can't say that it's GPL until
he releases a new source code saying that it's GPL and not NPL.

Thank you very much!

Best regards,
Nelson