[O] Can't remove deadline or schedule in bulk mode

[Julien Cubizolles]

In an agenda buffer, C-u B d should clear the deadline of the entries
marked the way C-u does on a single entry. I think it's what it used to
do some time ago. Instead, I get:

--8<---------------cut here---------------start------------->8---
org-agenda-deadline: Invalid function: 4
--8<---------------cut here---------------end--------------->8---

Julien.