Preemption sometimes does not respect heartbeats between preemptions

Running org.apache.tez.analyzer.TestAnalyzer
Tests run: 13, Failures: 2, Errors: 0, Skipped: 0, Time elapsed: 99.595 sec <<< FAILURE!
testBasicInputFailureWithoutExit(org.apache.tez.analyzer.TestAnalyzer)  Time elapsed: 6.276 sec  <<< FAILURE!
java.lang.AssertionError: v2 : 000000_0
	at org.junit.Assert.fail(Assert.java:88)
	at org.junit.Assert.assertTrue(Assert.java:41)
	at org.apache.tez.analyzer.TestAnalyzer.verifyCriticalPath(TestAnalyzer.java:273)
	at org.apache.tez.analyzer.TestAnalyzer.runDAGAndVerify(TestAnalyzer.java:220)
	at org.apache.tez.analyzer.TestAnalyzer.testBasicInputFailureWithoutExit(TestAnalyzer.java:399)

testCascadingInputFailureWithExitSuccess(org.apache.tez.analyzer.TestAnalyzer)  Time elapsed: 5.986 sec  <<< FAILURE!
java.lang.AssertionError: v3 : 000000_1
	at org.junit.Assert.fail(Assert.java:88)
	at org.junit.Assert.assertTrue(Assert.java:41)
	at org.apache.tez.analyzer.TestAnalyzer.verifyCriticalPath(TestAnalyzer.java:273)
	at org.apache.tez.analyzer.TestAnalyzer.runDAGAndVerify(TestAnalyzer.java:220)
	at org.apache.tez.analyzer.TestAnalyzer.testCascadingInputFailureWithExitSuccess(TestAnalyzer.java:561)


Results :

Failed tests: 
  TestAnalyzer.testBasicInputFailureWithoutExit:399->runDAGAndVerify:220->verifyCriticalPath:273 v2 : 000000_0
  TestAnalyzer.testCascadingInputFailureWithExitSuccess:561->runDAGAndVerify:220->verifyCriticalPath:273 v3 : 000000_1