HADOOP-9459. ActiveStandbyElector can join election even before Service HEALTHY, and results in null data at ActiveBreadCrumb. Contributed by Vinay and Todd Lipcon.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1482226 13f79535-47bb-0310-9956-ffa450edef68