**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.

it('should reset internal state if removed then readded', function() {
    
    var props = {
      usernameToStatus: {
        jcw: 'jcwStatus',
      },
    };
    var container = document.createElement('div');
    var parentInstance = ReactDOM.render(
      <FriendsStatusDisplay {...props} />,
      container
    );
    var statusDisplays = parentInstance.getStatusDisplays();
    var startingInternalState = statusDisplays.jcw.getInternalState();
    
    ReactDOM.render(
      <FriendsStatusDisplay />,
      container
    );
    statusDisplays = parentInstance.getStatusDisplays();
    expect(statusDisplays.jcw).toBeFalsy();
    
    ReactDOM.render(
      <FriendsStatusDisplay {...props} />,
      container
    );
    statusDisplays = parentInstance.getStatusDisplays();
    expect(statusDisplays.jcw).toBeTruthy();
    expect(statusDisplays.jcw.getInternalState())
        .not.toBe(startingInternalState);