MAPREDUCE-3392. Fixed Cluster's getDelegationToken's API to return null when there isn't a supported token. (John George via vinodkv) - Merging r1200484 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23.0@1201064 13f79535-47bb-0310-9956-ffa450edef68
3 files changed