Changes to Copyright: header after copyright assignment

[Glenn Morris]

If John Smith is the author of foo.el, with Copyright header:

Copyright (C) 2000, 2002, 2004  John Smith <address@hidden>

and in 2004 he assigns the copyright to the FSF so that foo.el can be
included in Emacs, should the Copyright in the Emacs version of foo.el
read:

Copyright (C) 2004  Free Software Foundation, Inc.
Copyright (C) 2000, 2002, 2004  John Smith <address@hidden>

or just:

Copyright (C) 2000, 2002, 2004  Free Software Foundation, Inc.

or something else?

Maintain.texi "Copyright Notices" suggests the latter:

   For an FSF-copyrighted package, if you have followed the procedures
   to obtain legal papers, each file should have just one copyright
   holder: the Free Software Foundation, Inc.

but I'm unsure about being revisionist (as it were).

I guess this is not an Emacs-specific question, but someone here will
probably know. Thanks in advance.