func (l Label) Abs(repo, pkg string) Label {
	if !l.Relative {
		return l
	}
	return Label{Repo: repo, Pkg: pkg, Name: l.Name}
}
func (l Label) Abs(repo, pkg string) Label {
	if !l.Relative {
		return l
	}
	return Label{Repo: repo, Pkg: pkg, Name: l.Name}
}
// Abs computes an absolute label (one with a repository and package name)
// from this label. If this label is already absolute, it is returned
// unchanged.