Extracted from https://github.com/facebook/react/issues/12643.

We're currently diff a host node in the complete phase even if it has bailed out in the begin phase. By itself, this just means we're doing a little bit more work than necessary. But it also has some observable effects. In particular, https://github.com/facebook/react/issues/13424 (which by itself would be very rare and probably not worth fixing) is made worse because we end up committing update to inputs from another component.

I have a fix for this in https://github.com/facebook/react/pull/13423. Filing this for posterity.
if (!root) {
        const container = {rootID: rootID, children: []};
        rootContainers.set(rootID, container);
        root = NoopRenderer.createContainer(container, isAsync, false);
        roots.set(rootID, root);
      }
      return root.current.stateNode.containerInfo;
    },
    createPortal(
      children: ReactNodeList,
      container: Container,
      key: ?string = null,
    ) {
      return ReactPortal.createPortal(children, container, null, key);
    },
    
    render(element: React$Element<any>, callback: ?Function) {
      ReactNoop.renderToRootWithID(element, DEFAULT_ROOT_ID, callback);
    },
    renderLegacySyncRoot(element: React$Element<any>, callback: ?Function) {
      const rootID = DEFAULT_ROOT_ID;
      const isAsync = false;