Just correcting an error in the title to something more relevant.
> 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 <m...@nicolasgoaziou.fr>
> Date: Tue Apr 18 11:55:27 2017 +0200
> org-agenda: `tags-todo' command type includes DONE keywords
>
> Julien.
