Mixins: props are not correctly mixed in when registered globally

[thenickname]

Vue.js version

2.0.2

Reproduction Link

https://github.com/thenickname/vue-global-mixin-bug

Steps to reproduce

Register a mixin with props globally:

Vue.mixin( {
  props : [ "myProp" ]
} );

Pass a prop value into any component:
<hello my-prop="foo"></hello>

What is Expected?

myProp becomes a prop of Hello.vue and the value of my-prop is "foo".

What is actually happening?

The value of my-prop is undefined

Notes

• props are correctly mixed in if registered directly in the component using
  mixins : [ { props : [ 'myProp' ] } ]
• default values are passed correctly but will never change
• clone the provided git repository and run npm run dev to see the bug
  • repo contains two components "Hello.vue" and "HelloWithLocalMixin.vue" that demonstrate the apparently buggy behavior
  • also see App.vue and main.js

[DotCoyote]

The bug is back in v2.1.8

[LinusBorg]

Then please open a new issue with a reproduction. Thanks! :)