Traceback (most recent call last):
  File "/usr/local/lib/pypy2.7/dist-packages/Twisted-15.4.0-py2.7-linux-x86_64.egg/twisted/internet/defer.py", line 501, in _startRunCallbacks
    self._runCallbacks()
  File "/usr/local/lib/pypy2.7/dist-packages/Twisted-15.4.0-py2.7-linux-x86_64.egg/twisted/internet/defer.py", line 588, in _runCallbacks
    current.result = callback(current.result, *args, **kw)
  File "/home/skynet/p2pool/p2pool/util/deferral.py", line 256, in gotResult
    it(res2)
  File "/home/skynet/p2pool/p2pool/util/deferral.py", line 233, in it
    res = gen.send(cur) # external code is run here
--- ---
  File "/home/skynet/p2pool/p2pool/util/deferral.py", line 284, in _worker
    self.func(*self.args, **self.kwargs)
  File "/home/skynet/p2pool/p2pool/util/expiring_dict.py", line 109, in
    self._expire_loop = expire_loop = deferral.RobustLoopingCall(lambda: self_ref().expire())
exceptions.AttributeError: 'NoneType' object has no attribute 'expire'

Unhandled Error
Traceback (most recent call last):
  File "/usr/local/lib/pypy2.7/dist-packages/Twisted-15.4.0-py2.7-linux-x86_64.egg/twisted/internet/defer.py", line 501, in _startRunCallbacks
    self._runCallbacks()
  File "/usr/local/lib/pypy2.7/dist-packages/Twisted-15.4.0-py2.7-linux-x86_64.egg/twisted/internet/defer.py", line 588, in _runCallbacks
    current.result = callback(current.result, *args, **kw)
  File "/home/skynet/p2pool/p2pool/util/deferral.py", line 256, in gotResult
    it(res2)
  File "/home/skynet/p2pool/p2pool/util/deferral.py", line 233, in it
    res = gen.send(cur) # external code is run here
--- ---
  File "/home/skynet/p2pool/p2pool/util/deferral.py", line 284, in _worker
    self.func(*self.args, **self.kwargs)
  File "/home/skynet/p2pool/p2pool/util/expiring_dict.py", line 109, in
    self._expire_loop = expire_loop = deferral.RobustLoopingCall(lambda: self_ref().expire())
exceptions.AttributeError: 'NoneType' object has no attribute 'expire'