TaskManagerRunnerTest is unstable

17:34:16.833 [INFO] Running org.apache.flink.runtime.taskexecutor.TaskManagerRunnerTest
17:34:19.872 [ERROR] Tests run: 2, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 3.036 s <<< FAILURE! - in org.apache.flink.runtime.taskexecutor.TaskManagerRunnerTest
17:34:19.880 [ERROR] testShouldShutdownOnFatalError(org.apache.flink.runtime.taskexecutor.TaskManagerRunnerTest)  Time elapsed: 0.353 s  <<< FAILURE!
java.lang.AssertionError: 

Expected: is <1>
     but: was <0>
	at org.apache.flink.runtime.taskexecutor.TaskManagerRunnerTest.testShouldShutdownOnFatalError(TaskManagerRunnerTest.java:59)