SuspenseList tail property not working on re-renders

<!-- Note: if the issue is about documentation or the website, please file it at: https://github.com/reactjs/reactjs.org/issues/new --> **Do you want to request a *feature* or report a *bug*?** I am reporting a possible bug or otherwise requesting clarification. **What is the current behavior?** When a component with a SuspenseList re-renders (such as when it is is passed a new resource), the SuspenseList component still respects the revealOrder="forwards" or revealOrder="backwards" prop but does not respect the tail="collapsed" or tail="hidden" prop. **If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem. Your bug will get fixed much faster if we can run your code and it doesn't have dependencies other than React. Paste the link to your JSFiddle (https://jsfiddle.net/Luktwrdm/) or CodeSandbox (https://codesandbox.io/s/new) example below:** https://codesandbox.io/s/exciting-cherry-g9uc9 In order to see bug: 1) Refresh the Code Sandbox browser and see that "Loading profile..." displays and "Loading posts..." does not due to the tail being collapsed. This is the expected behavior. 2) Press the "Next" button. Both "Loading Profile..." and "Loading posts..." display. The tail is no longer collapsed. **What is the expected behavior?** The expected behavior would be for the tail to be collapsed when pressing the "Next" button. "Loading profile..." should be displayed, but not "Loading posts..." **Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?** This affects only the experimental Concurrent Mode build of React.