**Do you want to request a _feature_ or report a _bug_?**

Report a bug.

**What is the current behavior?**

When testing components, `Warning: ReactComponentTreeDevtool: Missing React element for debugID 1 when building stack` is shown when calling `TestUtils.renderIntoDocument`.

**If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://jsfiddle.net or similar (template: https://jsfiddle.net/reactjs/69z2wepo/).**

https://github.com/angusfretwell/reproduce-debugid-warning (`npm install && npm test`).

**What is the expected behavior?**

According to #7187 this is an internal warning and shouldn't be displayed.

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**
- react@15.2.1
- react-addons-test-utils@15.2.1
- react-dom@15.2.1

I didn't receive this warning on 15.2.0.

return <a ref={props.saveA} />;
    }
    var Outer = React.createClass({
      saveA() {
        refCalled++;
      },
      componentDidMount() {
        this.setState({});
      },
      render() {
        return <Inner saveA={this.saveA} />;
      },
    });
    ReactTestUtils.renderIntoDocument(<Outer />);
    expect(refCalled).toBe(1);
  }
  it('ref called correctly for stateless component when __DEV__ = false', function() {
    var originalDev = __DEV__;
    __DEV__ = false;
    testRefCall();
    __DEV__ = originalDev;
  });
  it('ref called correctly for stateless component when __DEV__ = true', function() {
    var originalDev = __DEV__;
    __DEV__ = true;
    testRefCall();
    __DEV__ = originalDev;
  });
});