emacs minor mode optional argument

With GNU Emacs 21.4.1 and desktop save/restore enabled, loading
"mercurial.el" from ".emacs" breaks Emacs' initialization sequence
when the desktop restore code loads a file under Mercurial control.
The function 'desktop-create-buffer' passes an argument to each
minor mode it activates for the buffer.

contrib/mercurial.el

@@ -633,7 +633,7 b' the file."'
 						     (modified . "m")))))))
       status)))
 
-(defun hg-mode ()
+(defun hg-mode (&optional toggle)
   "Minor mode for Mercurial distributed SCM integration.
 
 The Mercurial mode user interface is based on that of VC mode, so if