old_contents: 
  import pluginmgr
  import pluginmgr_test
  
  
  # XXX need common plugin base
  plugin = pluginmgr.PluginManager('pluginmgr_test.plugins')
  
  @plugin.register('mod0')
  class Mod0(pluginmgr.PluginBase):
      pass
  
  
  
  
new_contents: 
  import pluginmgr
  from pluginmgr_test import plugin
  
  
  @plugin.register('mod0')
  class Mod0(pluginmgr.PluginBase):
      pass
  
  
  
  
subject: clean up test module