I've found these two failures and thing there were more:
```
======================================================================
FAIL: test_archivebot_frr (tests.archivebot_tests.TestArchiveBot)
Test archivebot for one site on wikipedia:frr
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/travis/build/wikimedia/pywikibot-core/tests/aspects.py", line 651, in wrapped_method
func(self, key)
File "/home/travis/build/wikimedia/pywikibot-core/tests/archivebot_tests.py", line 74, in test_archivebot
self.assertIsInstance(thread.timestamp, datetime)
AssertionError: None is not an instance of <class 'datetime.datetime'>
```
* https://travis-ci.org/wikimedia/pywikibot-core/jobs/71239095#L2678: en.wikipedia 3.4.2
* https://travis-ci.org/xZise/pywikibot-core/jobs/71284248#L2654: en.wikipedia 3.3.5