ZOOKEEPER-2052 Unable to delete a node when the node has no children (Hongchao Deng and Yip Ng via rakeshr)

git-svn-id: https://svn.apache.org/repos/asf/zookeeper/branches/branch-3.4@1634777 13f79535-47bb-0310-9956-ffa450edef68
Merge remote-tracking branch 'remotes/origin/branch-3.4' into branch-3.4