Paul Eggert <eggert@cs.ucla.edu> writes:
> My guess is that Nicolas ran 'make change-history' on a private branch
> and then merged the result into emacs-25.  This has never worked, and
> it's why Makefile.in tries to check for this sort of thing.

No, I changed the branch check on emacs-25 to check for emacs-25 instead
of master, and then ran make change-history-nocommit.

This worked without any problem.

Nico