Watcher in custom component is not fired when prop value is updated from another watcher

[sqal]

Vue.js version

1.0.22

Reproduction Link

http://www.webpackbin.com/4yVzt9qWZ

What is Expected?

When some data passed to custom component as a prop is updated inside watcher callback, then this change should be detected by prop watcher in custom component.

What is actually happening?

Watcher in custom component is not aware about this change. But when i update data passed to component directly, not inside watcher, then watcher callback inside custom component is fired properly.

I noticed this issue have appeared in 1.0.22 and does not occur in pevious versions of Vue.