IndexStoredIndexedCacheTest random test failures

testCacheReuse(org.infinispan.query.directoryinteraction.IndexStoredIndexedCacheTest)  Time elapsed: 0.124 sec  <<< FAILURE!
java.lang.AssertionError:
        at org.testng.AssertJUnit.fail(AssertJUnit.java:59)
        at org.testng.AssertJUnit.assertTrue(AssertJUnit.java:24)
        at org.testng.AssertJUnit.assertNotNull(AssertJUnit.java:267)
        at org.testng.AssertJUnit.assertNotNull(AssertJUnit.java:259)
        at org.infinispan.lucene.DirectoryIntegrityCheck.verifyDirectoryStructure(DirectoryIntegrityCheck.java:49)
        at org.infinispan.lucene.DirectoryIntegrityCheck.verifyDirectoryStructure(DirectoryIntegrityCheck.java:32)
        at org.infinispan.query.directoryinteraction.IndexStoredIndexedCacheTest.testIndexWritingAndFinding(IndexStoredIndexedCacheTest.java:80)
        at org.infinispan.query.directoryinteraction.IndexStoredIndexedCacheTest.testCacheReuse(IndexStoredIndexedCacheTest.java:87)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:483)
        at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:84)
        at org.testng.internal.Invoker.invokeMethod(Invoker.java:714)
        at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:901) 
        at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1231)
        at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:127)
        at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:111)
        at org.testng.TestRunner.privateRun(TestRunner.java:767)
        at org.testng.TestRunner.run(TestRunner.java:617)
        at org.testng.SuiteRunner.runTest(SuiteRunner.java:348) 
        at org.testng.SuiteRunner.access$000(SuiteRunner.java:38)
        at org.testng.SuiteRunner$SuiteWorker.run(SuiteRunner.java:382)
        at org.testng.internal.thread.ThreadUtil$2.call(ThreadUtil.java:64)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)