A simple helper file for migrating between git accounts. It isn't perfect but it works.

migrate_git.rb

#!/usr/bin/ruby

require 'clamp'

Clamp do
  option ["--allbranches","-a"], :flag, "port all branches"
  option ['-r', '--reponame'], 'reponame', 'Repository name, as a full https url'
  option ['--forkname', '-f'], 'forkname', 'Repository name, as a full https url', default: 'dotcom'
  option ['--shrink'], :flag, "Shrink the repo"

  def execute
    result = %x(git status 1> /dev/null 2>&1)
    if $? != 0
      puts "Please run in a git repo"
      fail
    end

    branches = allbranches? ? `git branch -a`.split(/\n/).map {|r| r.strip.gsub!(/remotes\/origin\/([a-z0-9_-]*)$/,'\1')}.uniq.reject(&:nil?) : []

    # back up config
    `cp .git/config .git/config_backup`

    `git fetch origin`
    `git remote add #{forkname} #{reponame}`

    branches = branches - ['master']
    branches.unshift('master')
    
    puts "Converting the following branches: \n#{branches.join("\n * ")}"
    branches.each do |branch|
      `git checkout -b #{branch} origin/#{branch}`
      `git pull`
      if shrink?
        `java -jar  ~/bfg-1.12.12.jar --strip-blobs-bigger-than 100M .`
        `git reflog expire --expire=now --all && git gc --prune=now --aggressive`
      end
      `git push --force -u #{forkname} #{branch}`
    end
  end
end