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

[Red Hat Bugzilla]

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

--- Comment #7 from Chris Evich  ---
IMHO, the between-versions behavior inconsistency is nearly always a hard-sell,
especially for something sooooo new.  While having it change like this is
frustrating for testing/development, it's somewhat to be expected.  We'll have
a much easier argument to make for this change if it can be pinned to a nastier
problem to expect end-users to workaround.  If we can't, then probably best
close this and fixup our tests with version-dependant behavior.