an App Engine app can be deployed with a specific version ID http://code.google.com/appengine/docs/python/config/appconfig.html
such that if the original app has this default domain: myapp.appspot.com
and you can point your own custom domain to this using Google Apps www.myapp.com --> (CNAME) myapp.appspot.com
BUT you can also upload a version identifier with your app and access it like this: newversion.myapp.appspot.com
What I am wondering is if it is possible to hook up a custom domain to this non-default version of the app? v2.myapp.com --> newversion.myapp.appspot.com ??
I dont think this is supported... but was hoping someone could verify (because I can't find any hard documentation saying "no you cant do this")
EDIT: if you're stumbling upon this... you can use the dispatch.yaml file to point to specific SERVICE but not VERSION... so there is still no "built-in" solution for this as of the end of 2017