[O] org-agenda time grid broken ?

[Julien Cubizolles]

I noticed today (I hadn't used it in a long time) that the today and/or
time-grid view in the agenda seems broken.

With emacs -Q running Org mode version 9.0.9 (release_9.0.9 @ 
/usr/share/emacs/26.0.50/lisp/org/)

(setq org-agenda-files '("~/tmp/test-org/todo.org"))

todo.org
--8<---------------cut here---------------start------------->8---
# -*- coding: utf-8 -*-
* Beach
<2017-08-05 sam. 14:00-15:00>
--8<---------------cut here---------------end--------------->8---

org-agenda gives, as expected:
--8<---------------cut here---------------start------------->8---
Week-agenda (W31):
Monday     31 July 2017 W31
Tuesday     1 August 2017
Wednesday   2 August 2017
Thursday    3 August 2017
Friday      4 August 2017
Saturday    5 August 2017
               8:00...... ----------------
              10:00...... ----------------
              12:00...... ----------------
  todo:       14:00-15:00 Beach
              14:00...... ----------------
              16:00...... ----------------
              18:00...... ----------------
              20:00...... ----------------
              23:17...... now - - - - - - - - - - - - - - - - - - - - - - - - -
Sunday      6 August 2017
--8<---------------cut here---------------end--------------->8---

However, with Org mode version 9.0.9 (release_9.0.9 @ 
/home/wilk/git-repositories/org-mode/lisp/)

the info for today are missing: org-agenda gives (notice Saturday is missing)

--8<---------------cut here---------------start------------->8---
Week-agenda (W31):
Monday     31 July 2017 W31
Tuesday     1 August 2017
Wednesday   2 August 2017
Thursday    3 August 2017
Friday      4 August 2017
--8<---------------cut here---------------end--------------->8---

and attempting to switch to the day view gives the following message

--8<---------------cut here---------------start------------->8---
org-agenda-check-type: No Org agenda currently displayed
--8<---------------cut here---------------end--------------->8---

Did I miss an important change to the way org-agenda-files is to be
used ?

Julien.