notmuch-emacs: Fcc to top-level directory given by database.path

[Jani Nikula]

On Sat, 30 Sep 2017, Jani Nikula <jani at nikula.org> wrote:
> On Sat, 23 Sep 2017, David Bremner <david at tethera.net> wrote:
>> Do you happen to know if it calls with an empty string as the folder
>> name? It would be consistent with searching for that to insert at the
>> top level.
>
> notmuch insert --folder= or --folder="" does not work:
>
> String argument for option "folder" must be non-empty.
> Unrecognized option: --folder=
>
> It seems that our argument parser doesn't accept empty strings at all,
> which is a bit of a limitation. It would be logical for the empty string
> to work here, and AFAICT the notmuch insert code would handle this if
> the argument was let through the parsing.

Turns out this is trivial to address on top of the arg parsing series:
id:20171002162552.4827-1-jani at nikula.org.

BR,
Jani.