[O] clock-out broken?

[Robert Eckl]

Hi,
with some changes from today seems clocking out is broken:

  Clock starts at [2013-04-04 Do 01:22] - showing entire task time.
  Clock stopped at [2013-04-04 Do 01:22] after 0:00
  org-clocking-buffer: Wrong type argument: markerp, nil
  org-check-running-clock: Wrong type argument: markerp, nil [3 times]
  Modified buffers exist; exit anyway? (y or n)  y

It's not possible to stop emacs, theres an endless loop 

  org-clocking-buffer: Wrong type argument: markerp, nil  
  Modified buffers exist; exit anyway? (y or n)  y
 
FWIW, the entry expects a note for stopped clock

Emacs/24.3.50 linux mint 
Org-mode version 8.0-pre (release_8.0-pre-245-gde4d52

Cu
Robert