def extract_repo(path, destination, reference)
      fail 'Git not installed' unless Utils.command? 'git'
      Dir.chdir path do
        system "git archive #{reference} | tar -x -C #{destination}"
      end
    end
def extract_repo(path, destination, reference)
      fail 'Git not installed' unless Utils.command? 'git'
      Dir.chdir path do
        system "git archive #{reference} | tar -x -C #{destination}"
      end
    end
Extract repository files at a particular reference to directory.