Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/nodepool/nodepool.py", line 1900, in run
    self.updateConfig()
  File "/usr/lib/python2.7/site-packages/nodepool/nodepool.py", line 1873, in updateConfig
    self.reconfigureManagers(config)
  File "/usr/lib/python2.7/site-packages/nodepool/nodepool.py", line 1563, in reconfigureManagers
    provider_manager.ProviderManager(p)
  File "/usr/lib/python2.7/site-packages/nodepool/provider_manager.py", line 261, in __init__
    self.resetClient()
  File "/usr/lib/python2.7/site-packages/nodepool/provider_manager.py", line 312, in resetClient
    self._client = self._getClient()
  File "/usr/lib/python2.7/site-packages/nodepool/provider_manager.py", line 294, in _getClient
    **self.provider.cloud_config.config)
  File "/usr/lib/python2.7/site-packages/shade/openstackcloud.py", line 169, in __init__
    cache_expiration_time = int(cloud_config.get_cache_expiration_time())
TypeError: 'NoneType' object is not callable