Determines which branches are discovered.
Exclude branches that are also filed as PRs
If you are discovering origin pull requests, it may not make sense to discover the same changes both as a pull request and as a branch.
Only branches that are also filed as PRs
Discovers branches that have PR's associated with them. This may make sense if you have a notification sent to the team at the end of a triggered build or limited Jenkins resources.
All branches
Ignores whether the branch is also filed as a pull request and instead discovers all branches on the origin repository.