Auto-fill-mode bug: unbreakable space lost

[Gaetan Leurent]

- Steps to reproduce with a recent CVS emacs:

start emacs -Q

switch some buffer to text-mode: M-x text-mode
activate auto-fill-mode: M-x auto-fill-mode

insert the following text:
blahblah blahblah blahblahblah blahblah blahblahblah blahblah blahblah blah
(note that the last space is an unbreakable one)

put the point before the unbreakable space, and insert a normal space

the unbreakable space disappears when the text warps (fill-column should
be 70)


- This behavior seems wrong to me: I think the unbreakable space should
be kept. Besides, it was kept in emacs 21.3.

- With a CVS version from 2005-02-21 with the multi-tty patch, emacs
even crashes after trying a couple of time in a Gnus buffer (but not in
a regular text-mode buffer). This no longer happens with a recent CVS,
but I suspect there is (or was) something really wrong somewhere.