tags-todo error with #+FILETAGS: enseignement

[Julien Cubizolles <j.cubizolles@free.fr>]

When an entry inherits a tag from a #+FILETAGS: line, all its parents
get matched by a tags-todo agenda, even when they don't have a todo
keyword.

Consider the following:

--8<---------------cut here---------------start------------->8---
(setq org-agenda-files '("/home/wilk/tmp/test-org/test-todo.org"))
(setq org-agenda-custom-commands
      (quote (
	      ("wt" "Boulot"
	       (
		(tags-todo "enseignement")
		)
	       )
	      )))
(org-agenda)
--8<---------------cut here---------------end--------------->8---

with the following test-todo.org :

--8<---------------cut here---------------start------------->8---
#+FILETAGS: enseignement
* Contenu
** TODO Cours électrocinétique
--8<---------------cut here---------------end--------------->8---

The agenda called by "org-agenda w t" displays the "Cours
électrocinétique" (as it should) but also the "Contenu" even though it
doesn't have a TODO keyword.

The offending commit is:

commit 942b6267a09e167ad3a546e83205601aa5c0704e
Author: Nicolas Goaziou <mail@nicolasgoaziou.fr>
Date:   Tue Apr 18 11:55:27 2017 +0200
    org-agenda: `tags-todo' command type includes DONE keywords

Julien.