[Bug 1096293] `docker start` doesn't fail on started container

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1096293

--- Comment #6 from Daniel Walsh  ---
Lukas.  I agree I think this one should be fixed.  I think docker start should
tell you the container is already started.

But since the app is controlled by upstream, we only have the ability to send
patches.