bug#29924: [PATCH] Preserve special abbrev properties when writing

[Noam Postavsky]

Allen Li <vianchielfaura@gmail.com> writes:

> Apologies, the original patch is incorrect because define-abbrev
> requires passing :count as a keyword argument unlike the obsolete
> calling convention.
>
> Attached is a new patch, which unfortunately does not preserve the old
> abbrev file writing format. However, any recent version of Emacs will
> be able to accept this format for define-abbrev, and the previously
> written abbrev file format is documented as obsolete, so now is as
> good a time as any.

I think it would be helpful to have a basic test to ensure we preserve
round-tripping.