Merge 1550620 from trunk: HDFS-5652. Refactor invalid block token exception handling in DFSInputStream. (Liang Xie via junping_du)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1550623 13f79535-47bb-0310-9956-ffa450edef68