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.
static childContextTypes = {
        foo: PropTypes.string.isRequired,
        getFoo: PropTypes.func.isRequired,
      };
      getChildContext() {
        return {
          foo: this.props.bar,
          getFoo: () => this.props.bar,
        };
      }
      render() {
        return ReactDOM.createPortal(<Component />, portalContainer);
      }
    }
    ReactDOM.render(<Parent bar="initial" />, container);
    expect(portalContainer.innerHTML).toBe('<div>initial-initial</div>');
    expect(container.innerHTML).toBe('');
    ReactDOM.render(<Parent bar="changed" />, container);
    expect(portalContainer.innerHTML).toBe('<div>changed-changed</div>');
    expect(container.innerHTML).toBe('');
  });
  it('findDOMNode should find dom element after expanding a fragment', () => {
    class MyNode extends React.Component {