[O] org-toggle-checkbox does not work on entry with logbook entries

[Matt Lundin]

When I call org-toggle-checkbox on the following headline:

--8<---------------cut here---------------start------------->8---
* An entry with logbook entries
  SCHEDULED: <2011-03-19 Sat 08:00 .+1d>
  :LOGBOOK:
  CLOCK: [2011-03-23 Wed 08:07]
  - State "DONE"       from "NOW"        [2011-03-18 Fri 13:44]
  CLOCK: [2011-03-18 Fri 13:11]--[2011-03-18 Fri 13:44] =>  0:33
  - State "DONE"       from "NOW"        [2011-03-01 Tue 08:51]
  :END:

 - [ ] Item one
 - [ ] Item two
 - [ ] Item three
--8<---------------cut here---------------end--------------->8---

All the items are checked correctly.

--8<---------------cut here---------------start------------->8---
 - [X] Item one
 - [X] Item two
 - [X] Item three
--8<---------------cut here---------------end--------------->8---

But when I call org-toggle-checkbox on the entry again, the items are
not unchecked.

If I remove the LOGBOOK drawer, everything works as expected.

Best,
Matt