Some tests in TestLocalMode fail on Windows

Test fails due to:

2014-09-07 21:23:57,715 INFO [CallbackExecutor] launcher.LocalContainerLauncher (LocalContainerLauncher.java:onFailure(257)) - Container: container_1410150237271_0001_00_000001: Execution Failed:
java.lang.IllegalArgumentException: Null user
at org.apache.hadoop.security.UserGroupInformation.createRemoteUser(UserGroupInformation.java:1161)
at org.apache.hadoop.security.UserGroupInformation.createRemoteUser(UserGroupInformation.java:1148)
at org.apache.tez.runtime.task.TezChild.handleNewTaskCredentials(TezChild.java:262)
at org.apache.tez.runtime.task.TezChild.run(TezChild.java:208)
at org.apache.tez.dag.app.launcher.LocalContainerLauncher$1.call(LocalContainerLauncher.java:299)
at org.apache.tez.dag.app.launcher.LocalContainerLauncher$1.call(LocalContainerLauncher.java:283)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)