[recipes.py] use argparse to set command automatically.

recipe_engine/bundle.py

 #!/usr/bin/env python
 # Copyright 2017 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 """Bundles a universe_view into a standalone folder.
 
 This captures the result of doing all the network operations that recipe_engine
 might do at startup to fetch repo code.
 
@@ skipping 620 matching lines @@
     help='Create a hermetically runnable recipe bundle.',
     description=(
       'Create a hermetically runnable recipe bundle. This captures the result'
       ' of all network operations the recipe_engine might normally do to'
       ' bootstrap itself.'))
   bundle_p.add_argument(
     '--destination', default='./bundle',
     type=os.path.abspath,
     help='The directory of where to put the bundle (default: %(default)r).')
 
-  bundle_p.set_defaults(command='bundle', func=main)
+  bundle_p.set_defaults(func=main)
 
 
 def main(package_deps, args):
   """
   Args:
     root_package (package.Package) - The recipes script in the produced bundle
       will be tuned to run commands using this package.
     universe (loader.RecipeUniverse) - All of the recipes necessary to support
       root_package.
     destination (str) - Path to the bundle output folder. This folder should not
       exist before calling this function.
   """
   universe = loader.RecipeUniverse(package_deps, args.package)
   destination = args.destination
   root_package = package_deps.root_package
 
   logging.basicConfig()
   destination = prepare_destination(args.destination)
   for pkg in universe.packages:
     export_package(pkg, destination, pkg == root_package)
   prep_recipes_py(universe, root_package, destination)
   LOGGER.info('done!')