When users create pods with rkt version n, the next version n+1 must be able to run them.

I don't know if we need to implement anything for this. Can you think of anything we miss for that?

• add tests to check that a pod created on a previous version can be started. A functional test could download rkt-v0.7.0.tar.gz from internet and prepare the pod with rkt-0.7.0 prepare .... Then, it would run it with rkt-current run-prepared ...
• add documentation about that stable on-disk format. doc: stable on-disk format #1271
• proper error message when a pod is invalid "rkt list" error after upgrading to 0.7.0 #1140. Fix in Use last-ditch manifest parser for error reporting #1266 / Use last-ditch manifest parser for error reporting #1471, requires appc/spec release