gclient sync got errors

[Mind Silly]

Hello, I had met troubles when I pull the V8 source codes.

OS: windows 10 with both  Visual Studio 2015 and Visual Studio 2017

Steps:

1. Download the depot_tools bundle and extract it to E:\\deopt_tools
   
2. Set environment DEPOT_TOOLS_WIN_TOOLCHAIN to 0 and add E:\\deopt_tools to system PATH
3. Run "gclient" for the first time  ---> OK
4. Run "fetch v8"  ---> Ok, v8 source codes has been download
5. Run "gclient sync" as https://github.com/v8/v8/wiki/Building-with-GN#prerequisite-build-dependencies said, but got error

E:\github>gclient sync
Syncing projects: 100% (23/23), done.
Running hooks:  86% (20/23) clang
________ running 'E:\depot_tools\win_tools-2_7_6_bin\python\bin\python.exe v8/tools/clang/scripts/update.py' in 'E:\github'
Updating Clang to 318667-1...
Downloading prebuilt clang
Downloading https://commondatastorage.googleapis.com/chromium-browser-clang/Win/clang-318667-1.tgz .......... Done.
Creating directory E:\github\v8\third_party\llvm-build\Release+Asserts
clang 318667-1 unpacked
Traceback (most recent call last):
  File "v8/tools/clang/scripts/update.py", line 925, in <module>
    sys.exit(main())
  File "v8/tools/clang/scripts/update.py", line 921, in main
    return UpdateClang(args)
  File "v8/tools/clang/scripts/update.py", line 457, in UpdateClang
    CopyDiaDllTo(os.path.join(LLVM_BUILD_DIR, 'bin'))
  File "v8/tools/clang/scripts/update.py", line 379, in CopyDiaDllTo
    dia_path = os.path.join(GetVSVersion().Path(), 'DIA SDK', 'bin', 'amd64')
  File "v8/tools/clang/scripts/update.py", line 366, in GetVSVersion
    vs_toolchain.SetEnvironmentAndGetRuntimeDllDirs()
  File "E:\github\v8\build\vs_toolchain.py", line 85, in SetEnvironmentAndGetRuntimeDllDirs
    os.environ['GYP_MSVS_OVERRIDE_PATH'] = DetectVisualStudioPath()
  File "E:\github\v8\build\vs_toolchain.py", line 164, in DetectVisualStudioPath
    ' not found.') % (version_as_year))
Exception: Visual Studio Version 2017 (from GYP_MSVS_VERSION) not found.
Error: Command 'E:\\depot_tools\\win_tools-2_7_6_bin\\python\\bin\\python.exe v8/tools/clang/scripts/update.py' returned non-zero exit status 1 in E:\github

Then I set GYP_MSVS_VERSION=2015, run "gclient sync" got the same errors.  Searching google not found useful solutions.  Only find some discussion in https://bugs.chromium.org/p/v8/issues/detail?id=6857

So what can I do to make it works?  Thanks~