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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.


const c = <Group key="c" />;
        return (
          <Surface width={150} height={200}>
            <Group ref={this.group}>
              {this.props.flipped ? [b, a, c] : [a, b, c]}
            </Group>
          </Surface>
        );
      }
    };
  });
  afterEach(() => {
    document.body.removeChild(container);
    container = null;
  });
  it('should have the correct lifecycle state', () => {
    let instance = <TestComponent />;
    instance = ReactTestUtils.renderIntoDocument(instance);
    const group = instance.group.current;
    
    expect(typeof group.indicate).toBe('function');
  });
  it('should render a reasonable SVG structure in SVG mode', () => {
    let instance = <TestComponent />;
    instance = ReactTestUtils.renderIntoDocument(instance);
    const expectedStructure = {
      nodeName: 'svg',
      width: '150',
      height: '200',
      children: [