TestClassFinder failing on occasion

Tests run: 11, Failures: 3, Errors: 0, Skipped: 0, Time elapsed: 1.913 sec <<< FAILURE! - in org.apache.hadoop.hbase.TestClassFinder
testClassFinderFiltersByClassInDirs(org.apache.hadoop.hbase.TestClassFinder)  Time elapsed: 0.028 sec  <<< FAILURE!
java.lang.AssertionError: expected:<-1> but was:<0>
	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.junit.Assert.assertEquals(Assert.java:542)
	at org.apache.hadoop.hbase.TestClassFinder.testClassFinderFiltersByClassInDirs(TestClassFinder.java:259)

testClassFinderCanFindClassesInDirs(org.apache.hadoop.hbase.TestClassFinder)  Time elapsed: 0.017 sec  <<< FAILURE!
java.lang.AssertionError: null
	at org.junit.Assert.fail(Assert.java:86)
	at org.junit.Assert.assertTrue(Assert.java:41)
	at org.junit.Assert.assertTrue(Assert.java:52)
	at org.apache.hadoop.hbase.TestClassFinder.testClassFinderCanFindClassesInDirs(TestClassFinder.java:223)

testClassFinderFiltersByNameInDirs(org.apache.hadoop.hbase.TestClassFinder)  Time elapsed: 0.018 sec  <<< FAILURE!
java.lang.AssertionError: expected:<-1> but was:<0>
	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.junit.Assert.assertEquals(Assert.java:542)
	at org.apache.hadoop.hbase.TestClassFinder.testClassFinderFiltersByNameInDirs(TestClassFinder.java:242)