bug#5805: 23.1; abbrev-insert does not protext itself with save-excursion

[Chong Yidong <cyd@stupidchicken.com>]

> In our code we use abbrev to dynamically expand certain
> keywords. However, the new lisp implementation is more eager in
> finding things to check, ie. it is able to look back past non-word
> characters to see if an abbrev is to be found.  In this situation it
> is essential to do save-excursion.
>
> Ideally, either insert-abbrev should do a save-excursion itself or all
> calls to it should.  In our code, expand-abbrev is call which
> internally calls abbrev-insert.
>
> Alternatively, is it the recommendation for user code to surround all
> "abbrev" calls with save-excursion now?

Do you have a recipe for reproducing a bug?  By default, the abbrev code
is not supposed to change point, so there should be no advantage adding
a save-excursion.  I don't see why we should constrain the ability of
user-defined functions in `abbrev-expand-functions' to change point, if
they want to.

Or do you mean save-match-data?