In the end I got it to work by cheating: I copied ispell.el in /usr/share/emacs/site-lisp/dictionaries-common to debian-ispell.el and the byte compilation went forward.
In the end I got it to work by cheating: I copied ispell.el in /usr/share/ emacs/site- lisp/dictionari es-common to debian-ispell.el and the byte compilation went forward.