This feature is experimental. Please share your experiences so we know what to keep or change.
Makes the cache assume that newRequest has the same response as the
already cached oldRequest.
Unpoly uses this internally when the user redirects from /old to /new.
In that case, both /old and /new will cache the same response from /new.
If an alias could be registered, newRequest is returned.
If oldRequest wasn't found in the cache, undefined is returned.