git.el: Pass an explicit argument to enable smerge-mode.

Without argument the mode is toggled, which would do the wrong thing
if the file was already open.

Signed-off-by: Alexandre Julliard <julliard@winehq.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/contrib/emacs/git.el b/contrib/emacs/git.el
index b92bbe8..53dd703 100644
--- a/contrib/emacs/git.el
+++ b/contrib/emacs/git.el
@@ -1058,7 +1058,7 @@
   (let ((info (ewoc-data (ewoc-locate git-status))))
     (find-file (git-fileinfo->name info))
     (when (eq 'unmerged (git-fileinfo->state info))
-      (smerge-mode))))
+      (smerge-mode 1))))
 
 (defun git-find-file-other-window ()
   "Visit the current file in its own buffer in another window."