class Bundler::Molinillo::DependencyGraph::DetachVertexNamed

def up(graph)
  return [] unless @vertex = graph.vertices.delete(name)
  removed_vertices = [@vertex]
  @vertex.outgoing_edges.each do |e|
    v = e.destination
    v.incoming_edges.delete(e)
    if !v.root? && v.incoming_edges.empty?
      removed_vertices.concat graph.detach_vertex_named(v.name)
    end
  end
  @vertex.incoming_edges.each do |e|
    v = e.origin
    v.outgoing_edges.delete(e)
  end
  removed_vertices
end