Revert of git_cl/gclient: use python2 (patchset #3 id:40001 of https://codereview.chromium.org/1437773002/ )

Reason for revert:
breaks git-bash on windows

Original issue's description:
> git_cl/gclient: use python2
> 
> Newer distros are defaulting /usr/bin/python to python3, so use python2
> explicitly so we continue working.
> 
> Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=297535

TBR=stip@chromium.org,sergeyberezin@chromium.org,vapier@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1442583004

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@297544 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/git_cl.py b/git_cl.py
index 8fa8a30..c212300 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2.7
+#!/usr/bin/env python
 # Copyright (c) 2012 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.