gsutil: add wrapper script for our pinned version

Sometimes developers need to run gsutil directly for their work.
They can use the version in the chroot, or install their own copy
in their system.  Lets add a simpler wrapper to the version we
have pinned in chromite already so they don't need a chroot/sdk,
and so they don't have to manage it themselves.

The wrapper is left in scripts/ rather than bin/ so that we don't
expose this via $PATH.  That could lead to weird infinite loops
or overriding versions people already have installed.

BUG=None
TEST=`./scripts/gsutil ...` works

Change-Id: I67f1f910a45cca291383c638f81c01614d4dfd3e
Reviewed-on: https://chromium-review.googlesource.com/1274425
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
diff --git a/scripts/gsutil.py b/scripts/gsutil.py
new file mode 100644
index 0000000..938012c
--- /dev/null
+++ b/scripts/gsutil.py
@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Copyright 2018 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Wrapper around gsutil.
+
+This takes care of downloading the pinned version we use in chromite.
+"""
+
+from __future__ import print_function
+
+import os
+
+from chromite.lib import gs
+
+
+def main(argv):
+  gsutil = gs.GSContext.GetDefaultGSUtilBin()
+  os.execv(gsutil, ['gsutil'] + argv)