react-portal bug on close

App.jsx

import React, { Component } from 'react';
import Portal from 'react-portal';

class PortalContents extends Component {
  render () {
    return <div onClick={this.props.closePortal}>close</div>;
  }

  componentDidMount() {
    console.log('portal contents mounted');
  }

  componentWillUnmount() {
    this.props.updateChildProp();
    console.log('portal contents will unmount');
  }
}

class App extends Component {
  constructor(props) {
    super(props);

    this.state = { ok: true };
  }

  updateChildProp = () => {
    console.log('child prop will update');
    this.setState({ ok: false }, () => { console.log('updated child prop'); })
  }

  render() {
    return (
      <div className="App">
        <Portal onClose={() => { console.log('portal closed'); }} openByClickOn={<div>open portal</div>}>
          <PortalContents childProp={this.state.ok} updateChildProp={this.updateChildProp} />
        </Portal>
      </div>
    );
  }
}

export default App;