Fix bug in the is_party_to method.
Fix bug in the is_party_to method.

This method would have thrown an error if the request had no neighbors.
This (mis)behavior has been fixed.

kimchanyoung/nghborly,nyc-mud-turtles-2015/nghborly,nyc-mud-turtles-2015/nghborly,kimchanyoung/nghborly,nyc-mud-turtles-2015/nghborly,kimchanyoung/nghborly