<!--
  Note: if the issue is about documentation or the website, please file it at:
  https://github.com/reactjs/reactjs.org/issues/new
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**Do you want to request a *feature* or report a *bug*?** Bug, I guess

**What is the current behavior?** 


```
  console.error node_modules/fbjs/lib/warning.js:33
    Warning: Detected multiple renderers concurrently rendering the same context provider. This is currently unsupported.
```

Steps to reproduce the behavior:
1. `git clone https://github.com/stereobooster/react-context-issue`
2. `cd react-context-issue`
3. `yarn`
4. `yarn test`

**What is the expected behavior?** no warning

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?** React 16.4. Browser not affected, because error is in node.js

Open this because of https://github.com/facebook/react/pull/13127#issuecomment-402527012

Issue happens because of Enzyme (https://github.com/airbnb/enzyme/issues/1693), code is unreleased, so I copy-pasted it from master. 

I'm looking for advice or some clue on how to fix this, so I would be able to create PR in Enzyme repo (or in React repo if this is the case). Thank you.


],
    });
    renderer.update(
      <div>
        <span key="d">D</span>
        <span key="c">C</span>
        <span key="b">B</span>
      </div>,
    );
    expect(renderer.toJSON()).toEqual({
      type: 'div',
      props: {},
      children: [
        {type: 'span', props: {}, children: ['D']},
        {type: 'span', props: {}, children: ['C']},
        {type: 'span', props: {}, children: ['B']},
      ],
    });
  });
  it('does the full lifecycle', () => {
    const log = [];
    class Log extends React.Component {
      render() {
        log.push('render ' + this.props.name);
        return <div />;
      }
      componentDidMount() {
        log.push('mount ' + this.props.name);
      }
      componentWillUnmount() {