So kerbin only fails to build when it's in buildbot testing mode. It complains that
spawn: Invalid argumentCMake Error at C:/d/buildbot/4030a21b/source/superbuild/projects/win32/scripts/freetype.build.cmake:8 (message): Failed to build freetypeCMake Error at C:/d/buildbot/4030a21b/build/superbuild/sb-freetype-build.cmake:47 (message): Failed with exit code 1
Windows is not helpful on providing enough info here.
I cannot reproduce it in local testing mode... Gonna wait for it to fail again tomorrow and find a way to get more info other than spawn: Invalid argument.