comment-region doesn't uncomment some lines in region

[Drew Adams]

In emacs-lisp-mode, `comment-region' on this as selected region, with prefix
arg of -5:

;;;;; (defun foo ()
;;;;;   "jjj jjjjj jjjjj jjjj jjjj jjjjj jjjj jjj jjjj jjjjjj
;;;;; kkkk kkk kkk kkkkkk kkkkk kkkkkkk kkkkkk kkkkkk kkk kkkk
;;;;; kkkk kkk kkk kkkkkk kkkkk kkkkkk kkkkkk kkk kkkk"
;;;;;   (interactive)
;;;;;   (foobar
;;;;;     (let (e)
;;;;;       (nada))))

In Emacs 20, it uncomments the entire defun, which I consider correct. In
Emacs 21, it uncomments each line except these two lines, which are
unchanged:

;;;;; kkkk kkk kkk kkkkkk kkkkk kkkkkkk kkkkkk kkkkkk kkk kkkk
;;;;; kkkk kkk kkk kkkkkk kkkkk kkkkkk kkkkkk kkk kkkk"

In GNU Emacs 21.3.50.1 (i386-mingw-nt5.1.2600)
 of 2004-07-26 on BERATUNG4
configured using `configure --with-gcc
(3.3) --cflags -I../../jpeg-6b-1/include -I../../libpng-1.2.4-1/include -I..
/../tiff-3.5.7/include -I../../xpm-nox-4.2.0/include -I../../zlib-1.1.4-1/in
clude'