TEZ-2437. FilterLinesByWord NPEs when run in Localmode (zjffdu)

(cherry picked from commit fac3222c768fbdfc8c1bbe55f94bc106900e6ae4)

Conflicts:
	CHANGES.txt
diff --git a/CHANGES.txt b/CHANGES.txt
index f16d278..f813f06 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -6,6 +6,7 @@
 INCOMPATIBLE CHANGES
 
 ALL CHANGES:
+  TEZ-2437. FilterLinesByWord NPEs when run in Localmode
   TEZ-2057. tez-dag/pom.xml contains versions for dependencies.
   TEZ-2282. Delimit reused yarn container logs (stderr, stdout, syslog) with task attempt start/stop events
   TEZ-2396. pig-tez-tfile-parser pom is hard coded to depend on 0.6.0-SNAPSHOT version.
diff --git a/tez-dag/src/main/java/org/apache/tez/client/LocalClient.java b/tez-dag/src/main/java/org/apache/tez/client/LocalClient.java
index 2f8da9c..dca9778 100644
--- a/tez-dag/src/main/java/org/apache/tez/client/LocalClient.java
+++ b/tez-dag/src/main/java/org/apache/tez/client/LocalClient.java
@@ -112,7 +112,6 @@
     // the TezClient is stopped, in order not to leak.
     if (dagAppMaster != null) {
       dagAppMaster.stop();
-      dagAppMaster = null;
     }
   }