SpringApplicationShutdownHookTests.runWhenContextIsBeingClosedInAnotherThreadWaitsUntilContextIsInactive fails on latest Spring Framework SNAPSHOT

[philwebb]

spring-projects/spring-framework@20970a4 has broken SpringApplicationShutdownHookTests.runWhenContextIsBeingClosedInAnotherThreadWaitsUntilContextIsInactive but it's not yet clear if the test or the framework change need to be modified.