fill comment problem

[Markus Rost]

Add two lines to buffer *scratch* as indicated:

===Buffer *scratch*=========================================
;; This buffer is for notes you don't want to save, and for Lisp evaluation.
;; If you want to create a file, visit that file with C-x C-f,
;; then enter the text in that file's own buffer.

a;
b;
============================================================

Put point behind "a;" and call M-q (fill-paragraph).  You get:

===Buffer *scratch*=========================================
;; This buffer is for notes you don't want to save, and for Lisp evaluation.
;; If you want to create a file, visit that file with C-x C-f,
;; then enter the text in that file's own buffer.

a; b;
============================================================

Certainly "b;" should not move behind a comment.  It won't, if you use
a two character word, like "bb;".  I think the problem is related with
the use of comment-start-skip in function fill-comment-paragraph.

Another experiment.  Prepare the buffer as follows:

===Buffer *scratch*=========================================
;; This buffer is for notes you don't want to save, and for Lisp evaluation.
;; If you want to create a file, visit that file with C-x C-f,
;; then enter the text in that file's own buffer.
;c
;d
;e
============================================================

Put point before ";c" and call M-q (fill-paragraph).  You get:

===Buffer *scratch*=========================================
;; This buffer is for notes you don't want to save, and for Lisp
;; evaluation.  If you want to create a file, visit that file with C-x
;; C-f, then enter the text in that file's own buffer.  ;c ;d ;e
============================================================

This does not break lisp code, but is somewhat unexpected.