**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.

jordanjcw: 'jordanjcwStatus',
          emptyUsername: null,
        },
      },
    ];
    testPropsSequence(PROPS_SEQUENCE);
  });
  it('should not insert empty children in the middle', function() {
    var PROPS_SEQUENCE = [
      {
        usernameToStatus: {
          jcw: 'jcwStatus',
          jordanjcw: 'jordanjcwStatus',
        },
      },
      {
        usernameToStatus: {
          jcw: 'jcwstatus2',
          skipOverMe: null,
          skipOverMeToo: null,
          definitelySkipOverMe: null,
          jordanjcw: 'jordanjcwstatus2',
        },
      },
    ];
    testPropsSequence(PROPS_SEQUENCE);
  });
  it('should insert one new child in the middle', function() {
    var PROPS_SEQUENCE = [
      {