In LocalBookkeeper, the Zookeeper server is started at 127.0.0.1 and the client tries to derive the localhost address using getLocalHost API. This has a few issues:
1. There is a possibility of using the ipv6 address for localhost and hence the client will try connecting to ::1, 2181 rather than 127.0.0.1:2181 (this happens commonly on OSX)
2. The getLocalHost API could sometimes return non-loopback addresses as well.
Since the 'localbookie' mode is used with the zookeeper in the same machine, we should use loopback addresses for all invocations. The patch does just that.