class Bundler::Molinillo::DependencyGraph

def detach_vertex_named(name)
  vertex = vertex_named(name)
  return unless vertex
  successors = vertex.successors
  vertices.delete(name)
  edges.reject! { |e| e.origin == vertex || e.destination == vertex }
  successors.each { |v| detach_vertex_named(v.name) unless root_vertices[v.name] || v.predecessors.any? }
end