However, should the HEAD hold off on recognizing -i=mi2 until the next
branch is cut? On the HEAD, -i=mi evolves by definition. However,
-i=mi2 is evolving as well :-(
That'd be best I think. I think that -i=mi2 specifies a fixed standard
and we don't have one yet; so how about -i=mi being different from
-i=mi1, but not adding -i=mi2 until we're ready to fix the interface?
I just looked, and I take the idea back. It means updating NEWS, DOC
and testsuite twice - just after the branch (to start the new interface)
and just before a branch (to freeze the new interface).