Args fix for gsutil.py

"--" is the hard keyword to separate gsutil commands from gsutil.py commands.

BUG=
R=dnj@chromium.org

Review URL: https://codereview.chromium.org/812223002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@293433 0039d316-1c4b-4281-b951-d872f2087c98

gsutil.py

@@ -135,7 +135,11 @@ def parse_args():
   parser.add_argument('--target', default=DEFAULT_BIN_DIR)
   parser.add_argument('args', nargs=argparse.REMAINDER)
 
-  args = parser.parse_args()
+  args, extras = parser.parse_known_args()
+  if args.args and args.args[0] == '--':
+    args.args.pop(0)
+  if extras:
+    args.args = extras + args.args
   return args.force_version, args.fallback, args.target, args.args