I want a new build to occur:

• When a  branch backing a Pull Request is created or updated
• When master is updated (basically, when a PR is merged to master)

It appears that I can do the first by choosing "Discover Branches: Only branches that are also filed as PR's". I can do the second by choosing "Filter by name: master".

But if I specify both, it seems to apply the name filter to discovered branches, so no PR's are ever discovered. Furthermore, it never builds master because master is never the subject of a PR (we have master locked against direct commits, as is common in enterprise development.)

My guess is this is doable, but the documentation and UI are very unclear.  If it's not doable, then this is a feature request.