Website unit tests throw React warnings due to memory leaks caused by <Transition />

[dcapo]

The website unit test suite output includes a warning about a memory leak in <Transition />:

Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in the componentWillUnmount method. in Transition (created by ModalAnimatedWrapper) in ModalAnimatedWrapper (created by Modal) in Modal (created by ShareProProfilePanel)

I believe this happens because the unit test finishes and unmounts the component before the transition finishes.