Question: How does the library deal with migrated documents a version above it?

[Lukejkw]

In a rolling deployment, each instance of the application is taken down after successfully creating a new instance of the application.

In this scenario, there is a chance that a new version of the application could write a document with the new schema and then an old instance of the application could read this new document.

As far as I can work out, this would clearly break serialization as the old instance of the application would never be able to migrate down.

This seems like a big flaw with on-the-fly migrations? How are others dealing with this scenario?