adaptive-fill bug?

[Katsumi Yamaoka]

Hi,

While I'm not sure of it since I don't use the adaptive-fill-mode
normally, I found something like a bug.  Try the following:

(with-temp-buffer
  (insert-char ?- 70)
  (let ((fill-column 70)
        (adaptive-fill-mode t))
    (fill-region (point-min) (point-max))))
 => "fill-prefix too long for specified width"

Is it reasonable that the form causes an error?  Similar errors
have occurred when decoding the text/enriched MIME messages which
contain long dash lines.  The enriched-decode function which runs
fill-region is performed then.

Though we can solve it for that case by binding adaptive-fill-mode
to nil, I'm hesitating to do so.  I appreciate any comment.

Regards,