old_contents: from fabric.api import cd, run, task
  
  try:
      import fabfile_local
      _pyflakes = fabfile_local
  except ImportError:
      pass
  
  @task
  def update():
      with cd("~/vagrant-installers"):
          run("git pull")
  
new_contents: from fabric.api import cd, env, run, task
  
  try:
      import fabfile_local
      _pyflakes = fabfile_local
  except ImportError:
      pass
  
  @task
  def update():
      with cd("~/vagrant-installers"):
          run("git pull")
  
  @task
  def all():
      "Run the task against all hosts."
      for _, value in env.roledefs.iteritems():
          env.hosts.extend(value)
  
  @task
  def role(name):
      "Set the hosts to a specific role."
      env.hosts = env.roledefs[name]
  
subject: Allow the targetting of specific roles with fabric