This allows us to continue on branched like v0.14.1, v0.14.2, and tag on
that branch. But it will merge those tags into master so git describe
picks up the changes.
This does some git magic to make sure you do not tag a branch with
v0.13.3 unless that branch is a decendant of the release-0.13 branch
upstream.
Don't allow v0.13.4 if v0.13.3 doesn't exit
Don't allow v0.13.3 if v0.13.3 already exits
We keep getting tags and branches wonky. This will land
v0.14.0 as an ancestor of master
v0.14.1 will NOT be an ancestor of master
I can do the later, it only a touch of git gymnastics, not really hard, but
we only occasionably do that today. (0.13.1 is an ancestor of master,
but 0.13.2 is not)