Cause CalledProcessErrors to return 2, since its an infra failure.

recipes.py

 #!/usr/bin/env python
 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Tool to interact with recipe repositories.
 
 This tool operates on the nearest ancestor directory containing an
 infra/config/recipes.cfg.
 """
@@ skipping 333 matching lines @@
   info_p.add_argument(
       '--recipes-dir', action='store_true',
       help='Get the subpath where the recipes live relative to repository root')
 
   args = parser.parse_args()
 
   if args.verbose:
     logging.getLogger().setLevel(logging.INFO)
 
   repo_root, config_file = get_package_config(args)
-  package_deps = package.PackageDeps.create(
-      repo_root, config_file, allow_fetch=not args.no_fetch,
-      overrides=args.project_override)
+
+  try:
+    package_deps = package.PackageDeps.create(
+        repo_root, config_file, allow_fetch=not args.no_fetch,
+        overrides=args.project_override)
+  except subprocess.CalledProcessError:
+    # A git checkout failed somewhere. Return 2, which is the sign that this is
+    # an infra failure, rather than a test failure.
+    return 2
 
   if args.command == 'fetch':
     # We already did everything in the create() call above.
     assert not args.no_fetch, 'Fetch? No-fetch? Make up your mind!'
     return 0
   if args.command == 'simulation_test':
     return simulation_test(package_deps, args)
   elif args.command == 'lint':
     return lint(package_deps, args)
   elif args.command == 'run':
@@ skipping 21 matching lines @@
 
     Warmly,
     recipes.py
     """
     return 1
 
   return 0
 
 if __name__ == '__main__':
   sys.exit(main())