After submitting this bug report I noticed that somehow python2.6 dateutil was used - this happened because I had PYTHONPATH=/usr/lib/python2.6/dist-packages/ environment variable (I think I created it very long time ago for some reason; not sure how I managed not to notice this before reporting). After I removed wrong PYTHONPATH everything works as expected. Sorry for the noise, will be more careful next time. Please close this report as invalid.
