2.0.14 -> 2.0.15 Why would skin break?

We attempted an upgrade from 2.0.14 to 2.0.15. We of course have a custom skin but have not modified any php code. After upgrading, then re-pointing to the original database, the skin layout is screwed up. Our we going about this wrong? Should we just selectively copy the changed PHP files? Where can I get a list of the files that were changed? I assume no database schema changes.

Thanks in advance for any help.

You can see the conflicts in the Upgrade center.