2018-01-29 2:34 GMT+01:00 Berry, Charles <ccberry@ucsd.edu>:

> > On Jan 28, 2018, at 3:24 PM, Nicolas Goaziou <mail@nicolasgoaziou.fr>
> wrote:
> >
> > Would you have an ECM? I don't know what is "the by-backend trick".
>
> Not a bug AFAICS.
>
> `by-backend' is a macro mentioned here:
>
> https://lists.gnu.org/archive/html/emacs-orgmode/2013-07/msg00500.html
>
> I guess it needs to use `org-export-current-backend' if it is to be
> handled in recent org versions.
>

Thanks for the pointer to the variable but that is not the problem.

You should have a look at commit  38be85124551083d269.
It prevents evaluation of the by-backend form in parameters.

-- 
Fabrice