Mark, IIRC you've got VS 2015? Anyone with VS 2015 installed (or the full CRT redistributable) is unaffected because the required file is already in their system path - this includes my build machine, which is why all my tkinter tests passed before pushing the release (currently figuring out a way to avoid this in future without needing extra machines).

This is also why I'm worried about extensions built with non-distutils based tools. Anyone with the compiler has the current version of vcruntime.dll, but users may not (this is the versioning issue - someone might build with vcruntime150.dll which then won't work with vcruntime140.dll, so I'm trying to just block the DLL entirely).