Determines which branches are discovered.

Exclude branches that are also filed as PRs

If you are discovering origin pull requests, you may not want to also build the source branches for those pull requests.

Only branches that are also filed as PRs

Similar to discovering origin pull requests, but discovers the branch rather than the pull request. This means env.GIT_BRANCH will be set to the branch name rather than PR-#. Also, status notifications for these builds will only be applied to the commit and not to the pull request.

All branches

Ignores whether the branch is also filed as a pull request and instead discovers all branches on the origin repository.