[users at bb.net] Upgrade failure 0.8.9 to 0.8.12?

[Dan Kegel]

Got a lot of these warnings while starting up after upgrading.
(Otherwise seems up and running at first glance, love finally having
clickable categories on the waterfall.)

2016-03-12 22:03:25-0800 [-] trying to load status pickle from
/home/buildbot/master-state/sandbox/g-speak/monit-ubu1204-master/builder
2016-03-12 22:03:25-0800 [-] Upgrading
buildbot.status.builder.BuilderStatus (of
buildbot.status.builder.BuilderStatus @ 159286120) to version 2
2016-03-12 22:03:25-0800 [-] re-writing upgraded builder pickle
2016-03-12 22:03:25-0800 [-] error while loading status pickle,
creating a new one
2016-03-12 22:03:25-0800 [-] error follows:
2016-03-12 22:03:25-0800 [-] Unhandled Error
        Traceback (most recent call last):
          File "/home/buildbot/master-state/sandbox/local/lib/python2.7/site-packages/twisted/internet/defer.py",
line 1274, in unwindGenerator
            return _inlineCallbacks(None, gen, Deferred())
          File "/home/buildbot/master-state/sandbox/local/lib/python2.7/site-packages/twisted/internet/defer.py",
line 1128, in _inlineCallbacks
            result = g.send(result)
          File "/home/buildbot/master-state/sandbox/buildbot-git/master/buildbot/config.py",
line 777, in reconfigService
            yield svc.reconfigService(new_config)
          File "/home/buildbot/master-state/sandbox/buildbot-git/master/buildbot/process/builder.py",
line 103, in reconfigService
            description=builder_config.description)
        --- <exception caught here> ---
          File "/home/buildbot/master-state/sandbox/buildbot-git/master/buildbot/status/master.py",
line 364, in builderAdded
            builder_status.saveYourself()
          File "/home/buildbot/master-state/sandbox/buildbot-git/master/buildbot/status/builder.py",
line 165, in saveYourself
            filename = os.path.join(self.basedir, "builder")
          File "/home/buildbot/master-state/sandbox/lib/python2.7/posixpath.py",
line 68, in join
            elif path == '' or path.endswith('/'):
        exceptions.AttributeError: 'NoneType' object has no attribute 'endswith'