I'm not sure I understand. Let's write it out: User 1 goes to homepage.com and gets served the canary html. User 1 sees they need the js file included on the

I'm not sure I understand. Let's write it out: User 1 goes to homepage.com and gets served the canary html. User 1 sees they need the js file included on the homepage, identified by it's hash $hash, and so it requests the file $hash from cnd.homepage.com/$hash. User 1 gets $hash and everything loads fine. User 2 goes to homepage.com and does not get the canary, so their browser requests $old_hash, and gets the old version of the file from cnd.homepage.com/$old_hash, and everything is fine? Unless you are talking about rolling out a new version of the cdn server along with the main website I don't see what the issue is here?