TRAMP: error when completing filename

[Chris Moore]

run:

  emacs -Q

type:

  C-x C-f /a:/ TAB

see backtrace (I loaded the source of tramp.el to get a better backtrace):

Debugger entered--Lisp error: (wrong-number-of-arguments (lambda (filename 
directory) "Like `file-name-completion' for tramp files." (unless 
(tramp-tramp-file-p directory) (error "tramp-handle-file-name-completion 
invoked on non-tramp directory `%s'" directory)) (with-parsed-tramp-file-name 
directory nil (try-completion filename (mapcar (lambda (x) (cons x nil)) 
(file-name-all-completions filename directory))))) 3)
  tramp-handle-file-name-completion("" "/a:/" file-exists-p)
  apply(tramp-handle-file-name-completion ("" "/a:/" file-exists-p))
  (if fn (apply (cdr fn) args) (tramp-run-real-handler operation args))
  (let ((fn ...)) (if fn (apply ... args) (tramp-run-real-handler operation 
args)))
  (progn (let (...) (if fn ... ...)))
  (unwind-protect (progn (let ... ...)) (set-match-data 
save-match-data-internal (quote evaporate)))
  (let ((save-match-data-internal ...)) (unwind-protect (progn ...) 
(set-match-data save-match-data-internal ...)))
  (save-match-data (let (...) (if fn ... ...)))
  (let ((tramp-locker t)) (save-match-data (let ... ...)))
  (progn (setq tramp-locked t) (let (...) (save-match-data ...)))
  (unwind-protect (progn (setq tramp-locked t) (let ... ...)) (setq 
tramp-locked tl))
  (let ((tl tramp-locked)) (unwind-protect (progn ... ...) (setq tramp-locked 
tl)))
  tramp-sh-file-name-handler(file-name-completion "" "/a:/" file-exists-p)
  apply(tramp-sh-file-name-handler file-name-completion ("" "/a:/" 
file-exists-p))
  (cond ((and completion ...) (tramp-run-real-handler operation args)) ((and 
completion ... ...) t) (foreign (apply foreign operation args)) (t 
(tramp-run-real-handler operation args)))
  (let* ((v ...) (multi-method ...) (method ...) (user ...) (host ...) 
(localname ...)) (cond (... ...) (... t) (foreign ...) (t ...)))
  (with-parsed-tramp-file-name filename nil (cond (... ...) (... t) (foreign 
...) (t ...)))
  (let* ((filename ...) (completion ...) (foreign ...)) 
(with-parsed-tramp-file-name filename nil (cond ... ... ... ...)))
  (progn (let* (... ... ...) (with-parsed-tramp-file-name filename nil ...)))
  (unwind-protect (progn (let* ... ...)) (set-match-data 
save-match-data-internal (quote evaporate)))
  (let ((save-match-data-internal ...)) (unwind-protect (progn ...) 
(set-match-data save-match-data-internal ...)))
  (save-match-data (let* (... ... ...) (with-parsed-tramp-file-name filename 
nil ...)))
  tramp-file-name-handler(file-name-completion "" "/a:/" file-exists-p)
  
read-file-name-internal("/usr/local/emacs22/share/emacs/22.0.91/lisp/net//a:/" 
"/usr/local/emacs22/share/emacs/22.0.91/lisp/net/" nil)
  minibuffer-complete()
  call-interactively(minibuffer-complete)
  read-file-name("Find file: " nil 
"/usr/local/emacs22/share/emacs/22.0.91/lisp/net/" nil)
  find-file-read-args("Find file: " nil)
  call-interactively(find-file)



In GNU Emacs 22.0.91.34 (i686-pc-linux-gnu, GTK+ Version 2.8.20)
 of 2006-12-19 on chrislap
X server distributor `The X.Org Foundation', version 11.0.70101000
configured using `configure  '--with-gtk' '--prefix' '/usr/local/emacs22' 
'--with-xpm' '--with-jpeg' '--with-png' '--with-gif''

Important settings:
  value of $LC_ALL: en_GB.UTF-8
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_GB.UTF-8
  locale-coding-system: utf-8
  default-enable-multibyte-characters: t