prow/config/jobs.go
func (br Brancher) RunsAgainstAllBranch() bool {
	return len(br.SkipBranches) == 0 && len(br.Branches) == 0
}
func (br Brancher) RunsAgainstAllBranch() bool {
	return len(br.SkipBranches) == 0 && len(br.Branches) == 0
}
// RunsAgainstAllBranch returns true if there are both branches and skip_branches are unset