svn merge -c 1393777 FIXES: 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-0.23@1400216 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -11,6 +11,8 @@ Release 0.23.5 - UNRELEASED
     HDFS-4016. back-port HDFS-3582 to branch-0.23 (Ivan A. Veselovsky via
     bobby)
 
+    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

@@ -241,6 +241,9 @@ 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()) {