transfer.rb

require 'octokit'

client = Octokit::Client.new(access_token: "<TOKEN>")

repos = client.repos('gds-attic')

repos.take(10).each do |repo|
  puts "archiving #{repo.url}..."
  client.post(
    "#{repo.url}/transfer",
    new_owner: "alphagov",
    accept: "application/vnd.github.nightshade-preview+json"
  )

  client.edit_repository(
    "alphagov/#{repo.name}",
    archived: true
  )
end