class Bundler::Molinillo::DependencyGraph

def initialize_copy(other)
  super
  @vertices = other.vertices.reduce({}) do |vertices, (name, vertex)|
    vertices.tap do |hash|
      hash[name] = vertex.dup.tap { |v| v.graph = self }
    end
  end
  @root_vertices = Hash[@vertices.select { |n, _v| other.root_vertices[n] }]
  @edges = other.edges.map do |edge|
    Edge.new(
      vertex_named(edge.origin.name),
      vertex_named(edge.destination.name),
      edge.requirements.dup
    )
  end
end