TestMRCJCFileOutputCommitter fails intermittently

java.lang.AssertionError: Output directory not empty expected:<0> but was:<4>
	at org.junit.Assert.fail(Assert.java:88)
	at org.junit.Assert.failNotEquals(Assert.java:743)
	at org.junit.Assert.assertEquals(Assert.java:118)
	at org.junit.Assert.assertEquals(Assert.java:555)
	at org.apache.hadoop.mapred.TestMRCJCFileOutputCommitter.testAbort(TestMRCJCFileOutputCommitter.java:153)