Redo the python check to look for the directories too.

bootstrap/win/win_tools.bat

 @echo off
 :: 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.
 
 :: This script will try to find if svn and python are accessible and it not,
 :: it will try to download it and 'install' it in depot_tools.
 
 :: Sadly, we can't use SETLOCAL here otherwise it ERRORLEVEL is not correctly
 :: returned.
 
-set WIN_TOOLS_ROOT_URL=http://src.chromium.org/svn/trunk/tools
+set WIN_TOOLS_ROOT_URL=https://src.chromium.org/svn/trunk/tools
 set GIT_BIN_DIR=git-1.8.0_bin
 
 :: Get absolute root directory (.js scripts don't handle relative paths well).
 pushd %~dp0..\..
 set WIN_TOOLS_ROOT_DIR=%CD%
 popd
 
 if "%1" == "force" (
   set WIN_TOOLS_FORCE=1
   shift /1
@@ skipping 83 matching lines @@
 :SVN_FAIL
 echo ... Failed to checkout svn automatically.
 echo Please visit http://subversion.tigris.org to download the latest subversion client
 echo before continuing.
 echo You can also get the "prebacked" version used at %WIN_TOOLS_ROOT_URL%/third_party/
 set ERRORLEVEL=1
 goto :END
 
 
 :PYTHON_CHECK
-:: If the batch file exists, skip the python check.
-set ERRORLEVEL=0
-if exist "%WIN_TOOLS_ROOT_DIR%\python.bat" goto :END
-if "%WIN_TOOLS_FORCE%" == "1" goto :PYTHON_INSTALL
-call python --version 2>nul 1>nul
-if errorlevel 1 goto :PYTHON_INSTALL
+if "%DEPOT_TOOLS_PYTHON_275%" == "1" goto :PY275_CHECK
+goto :PY26_CHECK
 
-:: We are done.
+
+:PY26_CHECK
+if not exist "%WIN_TOOLS_ROOT_DIR%\python_bin" goto :PY26_INSTALL
+if not exist "%WIN_TOOLS_ROOT_DIR%\python.bat" goto :PY26_INSTALL
 set ERRORLEVEL=0
 goto :END
 
 
-:PYTHON_INSTALL
-if "%DEPOT_TOOLS_PYTHON_275%" == "1" goto :PY275_INSTALL
-goto :PY26_INSTALL
+:PY275_CHECK
+if not exist "%WIN_TOOLS_ROOT_DIR%\python275_bin" goto :PY275_INSTALL
+if not exist "%WIN_TOOLS_ROOT_DIR%\python.bat" goto :PY275_INSTALL
+set ERRORLEVEL=0
+goto :END
 
 
 :PY275_INSTALL
 echo Installing python 2.7.5...
 :: Cleanup python directory if it was existing.
 if exist "%WIN_TOOLS_ROOT_DIR%\python275_bin\." rd /q /s "%WIN_TOOLS_ROOT_DIR%\python275_bin"
 if exist "%~dp0python275.zip" del "%~dp0python275.zip"
 echo Fetching from %WIN_TOOLS_ROOT_URL%/third_party/python275_bin.zip
 cscript //nologo //e:jscript "%~dp0get_file.js" %WIN_TOOLS_ROOT_URL%/third_party/python275_bin.zip "%~dp0python275_bin.zip"
 if errorlevel 1 goto :PYTHON_FAIL
@@ skipping 28 matching lines @@
 goto :END
 
 
 :returncode
 set WIN_TOOLS_ROOT_URL=
 set WIN_TOOLS_ROOT_DIR=
 exit /b %ERRORLEVEL%
 
 :END
 call :returncode %ERRORLEVEL%