deactivated account can break redirect

[chadwhitacre]

Over on #1170 I deactivate an account (set claimed_time=null) that had two accounts elsewhere attached. Now hitting https://www.gittip.com/deactivated-demisbellot/ gives a 500:

Traceback (most recent call last):
  File "aspen/website.py", line 81, in handle_safely
    response = self.handle(request)
  File "aspen/website.py", line 114, in handle
    response = request.resource.respond(request)
  File "aspen/resources/dynamic_resource.py", line 52, in respond
    exec self.pages[1] in context
  File "/app/www/%username/index.html.spt", line 21, in <module>
    participant = get_participant(request, restrict=False)
  File "gittip/utils/__init__.py", line 331, in get_participant
    to = participant.resolve_unclaimed()
  File "gittip/models/participant.py", line 184, in resolve_unclaimed
    , (self.username,)
  File "postgres/__init__.py", line 463, in one
    return cursor.one(sql, parameters, default)
  File "postgres/cursors.py", line 105, in one
    out = self._some(sql, parameters, lo=0, hi=1)
  File "postgres/cursors.py", line 132, in _some
    raise TooMany(self.rowcount, lo, hi)
TooMany: Got 2 rows; expecting 0 or 1.

https://app.getsentry.com/gittip/gittip/group/10448339/

[Changaco]

Closing in favor of #1395.