setState after componentWillMount and between render and componentDidMount causes Invariant Violation

[SlimFoster]

I have a situation where I simultaneously render multiple instances of the same component. During componentWillMount a check is made against one of the props passed to the component and an event may be raised that causes other components to update their state like in this example:

http://jsfiddle.net/rTv4n/

The problem seems to be that if one of the components' render method was called but the component has not yet been mounted and then you call setState, it throws this exception:

Uncaught Error: Invariant Violation: findComponentRoot(..., .0.$child1): Unable to find element. This probably means the DOM was unexpectedly mutated (e.g., by the browser). Try inspecting the child nodes of the element with React ID ``. react.js:15374

[sophiebits]

Interesting. Summary: When mounting something like:

<div>
  <A />
  <B />
</div>

If B calls setState on A in B's componentWillMount, then the DOM won't be populated with A's HTML yet. I suppose the setState call should be queued until A's componentDidMount is called.

cc @sebmarkbage

[sophiebits]

#1363 fixed this.