title: Don't show long options twice in print_help() from argparse
body: <p>I have the following code:</p>
  
  <pre><code>parser = argparse.ArgumentParser(description='Postfix Queue Administration Tool',
          prog='pqa',
          usage='%(prog)s [-h] [-v,--version]')
  parser.add_argument('-l', '--list', action='store_true',
          help='Shows full overview of all queues')
  parser.add_argument('-q', '--queue', action='store', metavar='&lt;queue&gt;', dest='queue',
          help='Show information for &lt;queue&gt;')
  parser.add_argument('-d', '--domain', action='store', metavar='&lt;domain&gt;', dest='domain',
          help='Show information about a specific &lt;domain&gt;')
  parser.add_argument('-v', '--version', action='version', version='%(prog)s 0.1')
  args = parser.parse_args()
  </code></pre>
  
  <p>Which gives me output like this:</p>
  
  <pre><code>%./pqa                                                                                                                        
  usage: pqa [-h] [-v,--version]
  
  Postfix Queue Administration Tool
  
  optional arguments:
    -h, --help            show this help message and exit
    -l, --list            Shows full overview of all queues
    -q &lt;queue&gt;, --queue &lt;queue&gt;
                          Show information for &lt;queue&gt;
    -d &lt;domain&gt;, --domain &lt;domain&gt;
                          Show information about a specific &lt;domain&gt;
    -v, --version         show program's version number and exit
  </code></pre>
  
  <p>I would very much like to know how I can 'group' commands that have two versions (ie. long options) which each also show a metavar.  </p>
  
  <p>This is mostly an aesthetic issue on my side, but I would still like to fix this. I have been reading manuals and texts on the internet, but either the information just isn't there or I am totally missing something here :)</p>