>>> pywikibot.User(pywikibot.Site(), '#1242976') == pywikibot.User(pywikibot.Site(), 'User:#1242976')
This is an autoblock ID, you can only use to unblock it.
Traceback (most recent call last):
  ...
  File "pywikibot/page.py", line 5537, in parse
    u"'{0}' has no title.".format(self._text))
pywikibot.exceptions.InvalidTitle: 'User:#1242976' has no title.