Regression: render components list with v-else & v-for

### Vue.js version
2.1.5

### Reproduction Link
https://jsfiddle.net/7jcoogfc/5/

### Steps to reproduce
Nothing to do, see output.
Using `v-if` and `v-else` to show message when empty list, or list of rendered components

### What is Expected?
List of 1,2,3,4 expected

### What is actually happening?
`undefined` rendered with 0 errors

In Vue.js 2.1.4 all works!