prow/config/jobs.go
func (br Brancher) ShouldRun(branch string) bool {
	if br.RunsAgainstAllBranch() {
		return true
	}

	// Favor SkipBranches over Branches
	if len(br.SkipBranches) != 0 && br.reSkip.MatchString(branch) {
		return false
	}
	if len(br.Branches) == 0 || br.re.MatchString(branch) {
		return true
	}
	return false
}
func (br Brancher) ShouldRun(branch string) bool {
	if br.RunsAgainstAllBranch() {
		return true
	}

	// Favor SkipBranches over Branches
	if len(br.SkipBranches) != 0 && br.reSkip.MatchString(branch) {
		return false
	}
	if len(br.Branches) == 0 || br.re.MatchString(branch) {
		return true
	}
	return false
}
// ShouldRun returns true if the input branch matches, given the whitelist/blacklist.