In the debian manual, it says
"This manual is free software; you may redistribute it and/or modify it
under
the terms of the GNU General Public License. Please refer to the license in
Appendix F, GNU General Public License."
It then includes verbatim the license which says
"Appendix F. GNU General Public License
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed."
Since the GPL cannot be changed or modified, henceforth there is a
contradiction that goes against the GPL by including the very wording of
the form license.
Because of this, the debian should consider removing the form license.
Or relicense the manual under the GFDL and putting Appendix F under an
invariant section, which I doubt since Debian doesnt consider the GFDL
with invariant clauses to be free documentation.