The new integration test shows the desired user-facing behavior, which
is to make it easy to login without a tenanted URL and to jump between
tenants.
Note that we track two things in the identity_token cookie: a signed
id, and the updated_at for the underlying Identity object. This allows
us to effectively cache on the Identity without having to hit the
database, by using an Identity::Mock object that is compatible with
etag and cache methods.
Mike Dalessio
1277cc065b