Visual Studio 2017 Installer May Break Visual Studio 2008 on WoW64

As it happened in my case, the Visual Studio 2017 installer (Community Edition, but maybe also other editions) may break an existing Visual Studio 2008 installation. Specifically, when you run Visual Studio 2008 under WoW64 (e.g., from a TeamCity agent or similar), the Visual Studio $(WindowsSdkDir) variable will be undefined after running the 2017 installer, causing builds to fail as the toolchain cannot find the Windows SDK. A fix that worked for me can be found here. Took me some time to fix the issue (specifically, because it only happened under TeamCity), and happened again after upgrading from VS2017 RC to final.