title: Make a command available for two groups in python click?
body: <p>I'm using click to write a cli program in Python, and I need to write something like this:</p>
  
  <pre><code>import click
  
  
  @click.group()
  def root():
      """root"""
      pass
  
  
  @root.group()
  def cli():
      """test"""
      pass
  
  
  @root.group()
  def cli2():
      """test"""
      pass
  
  
  @cli.command('test1')
  @cli2.command('test1')
  def test1():
      """test2"""
      print 1234
      return
  
  
  root()
  </code></pre>
  
  <p>but this will fail with:</p>
  
  <blockquote>
    <p>TypeError: Attempted to convert a callback into a command twice.</p>
  </blockquote>
  
  <p>How can I share the command between multiple groups?</p>