title: Tab completion with Python's Cmd.cmd
body: <p>After testing a while with the Cmd.cmd framework in python, I noticed a problem I don't know what to do about. Plus I believe to have this working some hours before (or I'm just crazy), so this is even more weird.</p>
  
  <p>I have the following example code, tested on both Windows and Linux systems (so it's not a Windows problem), but tab completion simply doesn't work.</p>
  
  <p>If I use the <em>exact same</em> code in Python 2 it does work on the Linux system (not on the Windows one though)</p>
  
  <pre><code>import cmd
  class Shell ( cmd.Cmd ):    
      def do_test ( self, params ):
          print( 'test: ' + params )
  
      def do_exit ( self, params ):
          return True
  
      def do_quit ( self, params ):
          return True
  
  if __name__ == '__main__':
      x = Shell()
      x.cmdloop()
  </code></pre>
  
  <p>Do you know why this happens, or what I can do, to make tab completion possible?</p>