YARN-2566. DefaultContainerExecutor should pick a working directory randomly. (Zhihai Xu via kasha)

(cherry picked from commit cc93e7e683fa74eb1a7aa2b357a36667bd21086a)

Conflicts:
	hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/DefaultContainerExecutor.java
HADOOP-11176. KMSClientProvider authentication fails when both currentUgi and loginUgi are a proxied user. Contributed by Arun Suresh.
(cherry picked from commit 0e57aa3bf689374736939300d8f3525ec38bead7)
(cherry picked from commit f3132eee1011b750158169c099b26ce8f6e2d1f4)
HDFS-7237. The command "hdfs namenode -rollingUpgrade" throws ArrayIndexOutOfBoundsException.