Vue.js version

2.0.1 / 2.0.2

Reproduction Link

https://codepen.io/toxic-johann/pen/yajwRO

Steps to reproduce

use a v-for to render component
in component, you have to write a v-for with template in it but not wrapped with a root element
open console, and run test() function

What is Expected?

open console, and run success() function

What is actually happening?

throw the warning

[Vue warn]: It seems there are duplicate keys that is causing an update error. Make sure each v-for item has a unique key.
and error
Uncaught (in promise) TypeError: Cannot read property 'tag' of undefined

it's the same situation as #3810
However, that one contains only two templates with v-if in nested v-for
And this one contains three templates with v-if

And in my project, i contain with more.
So, i also want to know, if there are more template in nested v-for, will it run good?