[recipes.py] move remote arg parsing to its module

recipe_engine/remote.py

 # Copyright 2016 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.
 
 from __future__ import print_function
 
 import contextlib
 import logging
 import os
 import shutil
@@ skipping 14 matching lines @@
     args.workdir = tempfile.mkdtemp(prefix='recipe_engine_remote_')
     logging.info('Created temporary workdir %s', args.workdir)
 
   try:
     yield
   finally:
     if workdir_tempdir:
       shutil.rmtree(args.workdir, ignore_errors=True)
 
 
-def main(args):
+def add_subparser(parser):
+  remote_p = parser.add_parser(
+      'remote',
+      description='Invoke a recipe command from specified repo and revision')
+  remote_p.add_argument(
+      '--repository', required=True,
+      help='URL of a git repository to fetch')
+  remote_p.add_argument(
+      '--revision',
+      help=(
+        'Git commit hash to check out; defaults to latest revision on master'
+        ' (refs/heads/master)'
+      ))
+  remote_p.add_argument(
+      '--workdir',
+      type=os.path.abspath,
+      help='The working directory of repo checkout')
+  remote_p.add_argument(
+      '--use-gitiles', action='store_true',
+      help='Use Gitiles-specific way to fetch repo (potentially cheaper for '
+           'large repos)')
+  remote_p.add_argument(
+      'remote_args', nargs='*',
+      help='Arguments to pass to fetched repo\'s recipes.py')
+
+  remote_p.set_defaults(
+    command='remote',
+    bare_command=True,
+    func=main,
+  )
+
+
+def main(_package_deps, args):
   with ensure_workdir(args):
     checkout_dir = os.path.join(args.workdir, 'checkout')
     revision = args.revision or 'refs/heads/master'
     if args.use_gitiles:
       backend_class = fetch.GitilesBackend
     else:
       backend_class = fetch.GitBackend
     backend = backend_class(checkout_dir, args.repository, True)
     backend.checkout(revision)
     recipes_cfg = package_io.PackageFile(
         package.InfraRepoConfig().to_recipes_cfg(checkout_dir))
     cmd = [
         sys.executable,
         os.path.join(
             checkout_dir,
             recipes_cfg.read().recipes_path,
             'recipes.py'),
     ] + args.remote_args
     logging.info('Running %r', cmd)
     return subprocess.call(cmd)