**Do you want to request a *feature* or report a *bug*?**

Feature

**What is the current behavior?**

While server rendering React DOM and then hydrating with a different structure, React rightly warns that there are inconsistencies. But when I first saw these warnings I was not sure exactly what was going wrong.

Here are a few of the warnings I have been receiving:

```
Warning: Did not find a matching <button> in <div>.

Warning: Did not find a matching <img> in <div>.

Warning: Did not expect server HTML to contain a <div> in <div>.
```

Only on that last error did I catch on that this was a problem with server-rendering and the inconsistencies between that and my client render (intentional at the moment while testing some things in unpure render functions).

**What is the expected behavior?**

Being more explicit that this was a rendering inconsistency between server and client.

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**

React v16-beta.1
updatePayload = [];
        }
      } else {
        
        
        (updatePayload = updatePayload || []).push(propKey, null);
      }
    }
    for (propKey in nextProps) {
      var nextProp = nextProps[propKey];
      var lastProp = lastProps != null ? lastProps[propKey] : undefined;
      if (
        !nextProps.hasOwnProperty(propKey) ||
        nextProp === lastProp ||
        (nextProp == null && lastProp == null)
      ) {
        continue;
      }
      if (propKey === STYLE) {
        if (__DEV__) {
          if (nextProp) {
            
            
            Object.freeze(nextProp);
          }
        }
        if (lastProp) {