Hystrix instrumenation tests are flaky

[PerfectSlayer]

Test suite

test no fallback results in error for toObservable block from dd-java-agent/instrumentation/hystrix-1.4/src/test/groovy/HystrixObservableTest.groovy.
Marked flaky by CircleCI

Error

Expected exception of type 'com.netflix.hystrix.exception.HystrixRuntimeException', but got 'java.util.concurrent.TimeoutException'
	at org.spockframework.lang.SpecInternals.checkExceptionThrown(SpecInternals.java:84)
	at org.spockframework.lang.SpecInternals.thrownImpl(SpecInternals.java:71)
	at HystrixObservableTest.test no fallback results in error for #action(HystrixObservableTest.groovy:278)
Caused by: java.util.concurrent.TimeoutException: Timed out waiting for child spans.  Received: 1
	at datadog.trace.agent.test.AgentTestRunner.blockUntilChildSpansFinished(AgentTestRunner.groovy:668)
	at datadog.trace.agent.test.AgentTestRunner.blockUntilChildSpansFinished(AgentTestRunner.groovy:652)
	at HystrixObservableTest.test no fallback results in error for #action_closure51(HystrixObservableTest.groovy:272)
	at HystrixObservableTest.test no fallback results in error for #action_closure51(HystrixObservableTest.groovy)
	at groovy.lang.Closure.call(Closure.java:412)
	at groovy.lang.Closure.call(Closure.java:406)
	at datadog.trace.agent.test.utils.TraceUtils.runUnderTrace(TraceUtils.groovy:54)
	at datadog.trace.agent.test.utils.TraceUtils.runUnderTrace(TraceUtils.groovy:43)
	at datadog.trace.agent.test.utils.TraceUtils.runUnderTrace(TraceUtils.groovy:35)
	at HystrixObservableTest.test no fallback results in error for #action(HystrixObservableTest.groovy:250)

Environment

Any version of Java and JVM.

Logs

hystrix-1.4.zip