TestFsDatasetImpl.testReportBadBlocks brittle

Failing for the past 1 build (Since #4 )
Took 7.4 sec.
Error Message
expected:<1> but was:<0>
Stacktrace
java.lang.AssertionError: expected:<1> but was:<0>
	at org.junit.Assert.fail(Assert.java:89)
	at org.junit.Assert.failNotEquals(Assert.java:835)
	at org.junit.Assert.assertEquals(Assert.java:647)
	at org.junit.Assert.assertEquals(Assert.java:633)

      dataNode.reportBadBlocks(block, dataNode.getFSDataset()
          .getFsVolumeReferences().get(0));
      Thread.sleep(3000);                                           // 3s sleep
      BlockManagerTestUtil.updateState(cluster.getNamesystem()
          .getBlockManager());
      // Verify the bad block has been reported to namenode
      Assert.assertEquals(1, cluster.getNamesystem().getCorruptReplicaBlocks());  // here