HDFS-3996. Add debug log removed in HDFS-3873 back. Contributed by Eli Collins

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1393778 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -26,6 +26,8 @@ Release 2.0.3-alpha - Unreleased
     HDFS-3896. Add descriptions for dfs.namenode.rpc-address and
     dfs.namenode.servicerpc-address to hdfs-default.xml. (Jeff Lord via atm)
 
+    HDFS-3996. Add debug log removed in HDFS-3873 back. (eli)
+
   OPTIMIZATIONS
 
   BUG FIXES 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/HftpFileSystem.java

@@ -254,6 +254,9 @@ public class HftpFileSystem extends FileSystem
                   ", assuming security is disabled");
               return null;
             }
+            if (LOG.isDebugEnabled()) {
+              LOG.debug("Exception getting delegation token", e);
+            }
             throw e;
           }
           for (Token<? extends TokenIdentifier> t : c.getAllTokens()) {