vimpulse-define-keyできないことがある?

• emacs23.1.1
• gitのmasterのvimpulse

(vimpulse-define-key 'emacs-lisp-mode 'vi-state "\  e" 'eval-last-sexp)
(vimpulse-define-key 'emacs-lisp-mode 'visual-state "\  e" 'eval-region)

とかしたいが動かなかったのでnilになるとこを消してみたら動いた.

--- a/vimpulse-viper-function-redefinitions.el
+++ b/vimpulse-viper-function-redefinitions.el
@@ -414,8 +414,9 @@ and remove duplicates."
                    (add-to-list 'result (cons aux toggle) t))))
              (when (memq major-mode vimpulse-auxiliary-modes)
                (setq aux (cdr (assq major-mode entry)))
-               (unless (assq aux result)
-                 (add-to-list 'result (cons aux toggle) t)))
+               (when aux
+                 (unless (assq aux result)
+                   (add-to-list 'result (cons aux toggle) t))))
              result))
           ;; regular mode
           (t