no local map in minibuffer

[Masatake YAMATO]

I found a situation where (current-local-map) returns nil in minibuffer.
I'll tell how to reproduce it here. Could you tell me this is the expected
behavior or not(bug)?
I tested this example with 
GNU Emacs 22.0.51.1 (i686-pc-linux-gnu, X toolkit, Xaw3d scroll bars, 
multi-tty) of 2006-01-20 on localhost.localdomain.

1. Run emacs with -Q 
2. Evaluate following code:

   (defun my-report-if-no-keymap ()
      (unless (current-local-map)
         (error "No local keymap"))) 
   (add-hook 'minibuffer-exit-hook 'my-report-if-no-keymap)

3. Type just M-x (here I expect the minibuffer history is empty.)
4. Type M-r
5. Give a something string to prompt, "Previous element matching (regexp): ".

   Previous element matching (regexp): foo

6. Type return key.

7. Emacs reports "No local keymap".
   I expect (current-local-map) returns a keymap but it returns nil.

Masatake YAMATO