Fix error where address is null in _get_host_info (elastic#506)

* Fix error where address is null in _get_host_info * Bump CI

Author: ytanay

elasticsearch/transport.py

@@ -219,8 +219,8 @@ def _get_host_info(self, host_info):
  host = {}
  address = host_info.get('http', {}).get('publish_address')
 
- # malformed address
- if ':' not in address:
+ # malformed or no address given
+ if not address or ':' not in address:
  return None
 
  host['host'], host['port'] = address.rsplit(':', 1)