Servers should always be upgraded before agents, but generally this
isn't required because things are compatible between versions. In this
case we're OK with failing closed if the user upgrades out of order, but
we should give a clearer message about what steps are required to fix
the issue.
Signed-off-by: Brad Davidson <brad.davidson@rancher.com>
(cherry picked from commit 31bbae1eb1f0372752a0479f19a3ce49ac30a24d)