title: SCons detects Visual C++ v14.2 (2019) but not v14.1 (2017)
body: <p>I need to build a dependency that uses SCons, and I need to build it with VC++2017, because another dependency I have cannot be built with VC++2019.</p>
  
  <p>SCons successfully detects VC++2019 (v14.2), but not VC++2017 (v14.1):</p>
  
  <pre><code>c:\Python27\Scripts\scons [...] --msvc-version=14.1 [...]
  scons: Reading SConscript files ...
  scons version: 3.1.1
  python version: 2 7 13 'final' 0
  
  scons: warning: VC version 14.1 not installed.  C/C++ compilers are most likely not set correctly.
   Installed versions are: ['14.2', '14.0', '11.0']
  [...]
  C++ compiler $CC does not work
  </code></pre>
  
  <p>I have installed Visual Studio 2019 Enterprise as well as Visual Studio 2019 Build Tools, and for both, I have installed the platform tools / compiler for v14.1 and x86/x64. Compiling with the VC++2017 platform tools works fine in Visual Studio 2019 as well as using MSBuild, so the problem seems to be with SCons only.</p>
  
  <p>How does SCons detect VC++2017 and VC++2019 and where should I start looking for the problem?</p>
  
  <p>(There are old threads about this, but most of them are about people wondering why the "classic" detection/config methods using registry and vcvars.bat no longer work, so these are not helpful)</p>