module Bundler::SharedHelpers

def with_clean_git_env(&block)
  keys    = %w[GIT_DIR GIT_WORK_TREE]
  old_env = keys.inject({}) do |h, k|
    h.update(k => ENV[k])
  end
  keys.each {|key| ENV.delete(key) }
  block.call
ensure
  keys.each {|key| ENV[key] = old_env[key] }
end