mailabbrev fix from Jan 2005 now broken in latest CVS

[John Owens <john_owens@yahoo.com>]

Greetings, I use the "wanderlust" mailer in emacs and asked for some
changes in January 2005 in "mailabbrev" to support auto-completion.
When I type an alias, if that alias has a '-' in it, it autocompleted
when the - is typed. The fix corrected this problem. Now the 
problem has returned.

Here was the original fix:

http://thread.gmane.org/gmane.emacs.devel/31657

(That actually fixed the problem of typing a '@' causing an autocomplete
so if you had an alias 'mark' and typed 'mark@foo.com', it would
autocomplete your 'mark' alias when you typed the '@'. But as I recall,
there was a '-' completion problem as well.)

It appears that revision 1.75 fixed this:

http://cvs.savannah.gnu.org/viewvc/emacs/lisp/mail/mailabbrev.el?revision=1.75&root=emacs&view=markup

(sendmail-pre-abbrev-expand-hook):
Don't expand if the character is @, period, dash, etc.

The only major change between now and then was rms's 1.82.2.1 / 1.83
change, and I'm suspecting that caused it. I confirmed that this
is the case by installing the previous version (the one right
before the 1.82.2.1 / 1.83 fix) 1.68.2.10, which does not exhibit
the problem. 

I can reproduce by calling compose-mail and typing an alias to be
expanded that has a '-' in it - it currently expands when the '-' 
is typed even if the alias continues after the '-' ('mark-h' for
instance).

JDO