Log files are created even if -nolog argument is set.
On the core '2.0' branch, http.py calls logoutput before args are parsed.
The whole log is as follows:
2013-10-02 21:18:41 http.py, 70 in <module>: VERBOSE Starting 1 threads...
This problem was removed from core 'master' when httplib2 was replaced with 'requests'.
To see the line causing this message:
$ git checkout 2.0 ... $ git grep 'Starting.*threads' pywikibot/comms/http.py:pywikibot.log(u'Starting %(numthreads)i threads...' % locals())