SlowBookieTest#testSlowBookie fails intermittently

junit.framework.AssertionFailedError: expected:<0> but was:<-559038737>
	at junit.framework.Assert.fail(Assert.java:47)
	at junit.framework.Assert.failNotEquals(Assert.java:283)
	at junit.framework.Assert.assertEquals(Assert.java:64)
	at junit.framework.Assert.assertEquals(Assert.java:195)
	at junit.framework.Assert.assertEquals(Assert.java:201)
	at org.apache.bookkeeper.client.SlowBookieTest.testSlowBookie(SlowBookieTest.java:82)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)