prow/gerrit/client/client.go
func (p ProjectsFlag) Set(value string) error {
	parts := strings.SplitN(value, "=", 2)
	if len(parts) != 2 {
		return fmt.Errorf("%s not in the form of host=repo-a,repo-b,etc", value)
	}
	host := parts[0]
	if _, ok := p[host]; ok {
		return fmt.Errorf("duplicate host: %s", host)
	}
	repos := strings.Split(parts[1], ",")
	p[host] = repos
	return nil
}
func (p ProjectsFlag) Set(value string) error {
	parts := strings.SplitN(value, "=", 2)
	if len(parts) != 2 {
		return fmt.Errorf("%s not in the form of host=repo-a,repo-b,etc", value)
	}
	host := parts[0]
	if _, ok := p[host]; ok {
		return fmt.Errorf("duplicate host: %s", host)
	}
	repos := strings.Split(parts[1], ",")
	p[host] = repos
	return nil
}
// Set populates ProjectsFlag upon flag.Parse()