So my opinion is that we revisit the policy a bit, and backtrack a the
mi-.*exp vs mi2-.*exp idea, get rid of the duplication, and call everything
"MI2", as it is in practice (must be, because that's how we run the tests).
When we really introduce an incompatible change that actually justifies MI3,
_then_ we should revisit the policy of whether to mass copying/rename tests, or
share them, depending on how big the difference between the versions would be,
and therefore depending on the practicality of the different options.
As is, the double testing seems just pointless to me.