bug#20495: 24.5; invoking Hunspell with multiple dicts

[Arash Esbati <esbati@gmx.de>]

I've been `abusing' Hunspell's feature with multiple dicts through
ispell.el.  Beginning with 24.4., it stopped working and the issue
persists in 24.5.  You can produce the error with:

1.  Start emacs with
emacs --eval '(setq debug-on-error t)' -Q &

2.  Eval: 
(setq
   ispell-local-dictionary-alist
   '((nil "[A-Za-z]" "[^A-Za-z]" "[']" nil
      ("-d" "en_US")
      nil iso-8859-1)
     ("deutsch8+american" 
      "[a-zA-Z\304\326\334\344\366\337\374]" 
      "[^a-zA-Z\304\326\334\344\366\337\374]" "[']" t
      ("-d" "de_DE,en_US")
      nil iso-8859-1)))

(global-set-key "\C-cia"
  '(lambda ()
     (interactive)
     (ispell-change-dictionary "deutsch8+american")))

3.  Hit `C-c i a' followed by `M-x ispell RET' which says:

--8<---------------cut here---------------start------------->8---
Debugger entered--Lisp error: (error "ispell-phaf: No matching entry for deutsch8+american.
")
  signal(error ("ispell-phaf: No matching entry for deutsch8+american.\n"))
  error("ispell-phaf: No matching entry for %s.\n" "deutsch8+american")
  ispell-parse-hunspell-affix-file("deutsch8+american")
  ispell-hunspell-fill-dictionary-entry("deutsch8+american")
  ispell-start-process()
  ispell-init-process()
  ispell-buffer-local-words()
  ispell-accept-buffer-local-defs()
  ispell-region(1 610)
  ispell-buffer()
  ispell()
  call-interactively(ispell record nil)
  command-execute(ispell record)
  execute-extended-command(nil "ispell")
  call-interactively(execute-extended-command nil nil)
  command-execute(execute-extended-command)
--8<---------------cut here---------------end--------------->8---

Eli kindly explained to me here
<http://thread.gmane.org/gmane.emacs.help/104130> that Hunspell does not
support multiple languages, but it looks like a bug in `ispell.el'.

Best, Arash