nested components A>B>A

[vird]

Similar to vuejs/vue#2519
Setting name doesn't help.

https://gist.github.com/vird/4a22d30cd6a5e876dd4df0e9a106b69a
usage

<ca level="5"></ca>

error:

vue.common.js?e881:1019[Vue warn]: Attribute "v-bind:level" is ignored on component <ca> because the component is a fragment instance: http://vuejs.org/guide/components.html#Fragment-Instance

[yyx990803]

This is a usage problem, vue-loader can't fix it for you.