Resolution: Not A Defect
Using the Ninja (or Ninja-multiconfig) generator on Windows, I can't find how to ensure Cmake sees the a particular Visual Studio environment, which I get by runnings the correct 'vsvarsall.bat'.
I can run vsvarsall.bat in a 'Execute Windows Batch Commands' step, and even invoke 'cl' in that step, but a following 'CMake build' step doesn't detect the compiler; I assume because it doesn't cascade the environment from the preceding step.
I don't want to add a particular Visual Studio the the global Jenkins PATH since there are several versions on the build machine.
Is there a way to make this work using the CMake build plugin? I want to avoid invoking cmake.exe manually in a 'Execute Windows Batch Command' step, since, well, that sucks.