[O] Turning on repeat logging for a subtree only

[Tom]

I generally have repeat logging off, but I want to turn it on
for a certain subtree.

I added the property LOGGING with the value logrepeat:

:PROPERTIES:
:LOGGING: logrepeat
:END:

But this doesn't seem to work, when I toogle the task state
the repeat is not logged.

I checked the source and apparently it is because logrepeat
sets org-log-repeat to 'state, but I want to it to be set to 'time.

Is there a way to set to it 'time instead of 'state?

And BTW why this 'state value is not documented in the docstring
of org-log-repeat? Isn't it a doc bug?

http://repo.or.cz/w/org-mode.git/blob/HEAD:/lisp/org.el#l2435