Comment 4 for bug 181401

And what team should own it.

So we need:
 - the idea of a series role for committers
 - that can be filled with an auto-generated team owned by the project owner/series owner (nb: ask curtis about plans here vis-a-vis series roles and project roles). If we want both, the project committer role could default to being in the series committer role.
 - that can then own the branch, and it can be called with the same of the series (e.g. trunk, 2.1 etc)
 - lastly only folk that can set the series branch in the web UI can can add new series branches like this