mercurial.el: ignore errors on hg-after-save-hook()

Don't signal an error even if running hg command fails.  Otherwise,
succeeding hooks won't be called.

contrib/mercurial.el

@@ -764,10 +764,11 b' Push changes G '
 (add-hook 'find-file-hooks 'hg-find-file-hook)
 
 (defun hg-after-save-hook ()
+  (ignore-errors
   (let ((old-status hg-status))
     (hg-mode-line)
     (if (and (not old-status) hg-status)
-	(hg-mode))))
+	  (hg-mode)))))
 
 (add-hook 'after-save-hook 'hg-after-save-hook)