Completion with (:exclusive 'no) is called twice, and doesn't pass over on sole completion.

Hi,

The completion in emacs 24 is called twice. For example

(defun foo-completion ()
  (when (save-excursion (re-search-backward "\\<\\w*" (point-at-bol) t))
    (let ((token (match-string-no-properties 0))
          (beg (match-beginning 0))
          (end (match-end 0)))
      (message "%s:" token)
      (when (= end (point))
        (list beg end (list "aaaa" "aaaaaaa" "bbbb" "truncat") :exclusive 'no)))))

(add-to-list 'completion-at-point-functions 'foo-completion)
;; it is now (foo-completion lisp-completion-at-point t)

Place your point at the end of 'aaaa and you try to complete. I am
getting

aaa:
aaaa:

in my message buffer. Which means the completion is called twice. I hope
this is not an intended behavior, as it might seriously interfere with
custom completion. For example I might want to have a different behavior
on the second consequent invocation of the completion (give a message,
modify the candidates etc).

Second problem is that if the completion is sole, the handling is not
passed over. For example after 'truncat I am getting a message "Sole
completion" and the lisp-completion-at-point is not reached at all. I
believe it's not how it should work.

In all the rest, new completion system is virtually perfect, thanks.

Vitalie.