Merge -r 1433878:1433879 from trunk to branch-2. Fixes: HADOOP-9212. Potential deadlock in FileSystem.Cache/IPC/UGI.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1433882 13f79535-47bb-0310-9956-ffa450edef68