**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
var isCustomComponentTag = isCustomComponent(type, props);
    }
    if (namespaceURI === HTML_NAMESPACE) {
      if (__DEV__) {
        warning(
          isCustomComponentTag || type === type.toLowerCase(),
          '<%s /> is using uppercase HTML. Always use lowercase HTML tags ' +
            'in React.',
          type,
        );
      }
      if (type === 'script') {
        
        
        var div = ownerDocument.createElement('div');
        div.innerHTML = '<script><' + '/script>'; 
        
        var firstChild = ((div.firstChild: any): HTMLScriptElement);
        domElement = div.removeChild(firstChild);
      } else if (props.is) {
        
        domElement = ownerDocument.createElement(type, {is: props.is});
      } else {
        
        
        
        domElement = ownerDocument.createElement(type);
      }
    } else {
      domElement = ownerDocument.createElementNS(namespaceURI, type);