YARN-24. Nodemanager fails to start if log aggregation enabled and namenode unavailable. (sandyr via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1461891 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9357. Fallback to default authority if not specified in FileContext. Contributed by Andrew Wang


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1461898 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-xxx-hadoop-auth-kerberos-realm-trunk-gd