keep-alive causes functional route component not rendered

[Centaur]

Vue.js & vue-router.js version

2.0.0-rc.6 & 2.0.0-rc.5

Reproduction Link

https://jsfiddle.net/oldpig/qos7px6j/6/

Steps to reproduce

run

What is Expected?

content of functional component Page1 should be rendered

What is actually happening?

Not rendered.

Observations:
If keep 'keep-alive' and remove functional : true, works as expected.
If remove keep-alive and keep functional: true, it gets rendered but class 'view' defined in router-view is not merged. I guess this can be reasoned from technical point of view, but it can still be very surprising at the first sight. So I think it may at least deserve a special treatment in the documentation.
If remove both, works as expected.

All these observations apply to jsx as well.

[yyx990803]

Functional components are instance-less and thus do not work with keep-alive (how do you cache something without an instance?). Short answer is do not use functional component as route components.