**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.

expect(refHopsAround.refs.divThreeRef).toEqual(thirdDiv);
    refHopsAround.moveRef();
    expect(refHopsAround.refs.divOneRef).toEqual(firstDiv);
    expect(refHopsAround.refs.hopRef).toEqual(secondDiv);
    expect(refHopsAround.refs.divThreeRef).toEqual(thirdDiv);
    refHopsAround.moveRef();
    expect(refHopsAround.refs.divOneRef).toEqual(firstDiv);
    expect(refHopsAround.refs.divTwoRef).toEqual(secondDiv);
    expect(refHopsAround.refs.hopRef).toEqual(thirdDiv);
    /**
     * Make sure that after the third, we're back to where we started and the
     * refs are completely restored.
     */
    refHopsAround.moveRef();
    expect(refHopsAround.refs.hopRef).toEqual(firstDiv);
    expect(refHopsAround.refs.divTwoRef).toEqual(secondDiv);
    expect(refHopsAround.refs.divThreeRef).toEqual(thirdDiv);
  });
  it('always has a value for this.refs', function() {
    var Component = React.createClass({
      render: function() {
        return <div />;
      },
    });
    var instance = ReactTestUtils.renderIntoDocument(<Component />);
    expect(!!instance.refs).toBe(true);
  });
  function testRefCall() {
    var refCalled = 0;
    function Inner(props) {