MAPREDUCE-7177. Disable speculative execution in TestDFSIO. Contributed by Zhaohui Xin.

(cherry picked from commit c991e2ca5a65eae62bad7e5baf81f1eb633b7ec0)
(cherry picked from commit faae522f520ba72796ec8db1a876cbe5e51245ce)

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-jobclient/src/test/java/org/apache/hadoop/fs/TestDFSIO.java

@@ -453,6 +453,7 @@ public class TestDFSIO implements Tool {
     job.setOutputKeyClass(Text.class);
     job.setOutputValueClass(Text.class);
     job.setNumReduceTasks(1);
+    job.setSpeculativeExecution(false);
     JobClient.runJob(job);
   }