> Uwe Brauer <oub@mat.ucm.es> writes:

   > FWIW, I tried a set-up with git (I don't have mercurial available) and I cannot
   > reproduce this.

Finally 

(setq backup-directory-alist '(("" . "~/.emacs.d/backup")))

Sort of solves my problem. (What I cannot see does not exist)