The cmake documentation
(https://cmake.org/cmake/help/v3.5/module/FindPythonLibs.html) says
that:
"If calling both find_package(PythonInterp) and
find_package(PythonLibs), call find_package(PythonInterp) first to get
the currently active Python version by default with a consistent version
of PYTHON_LIBRARIES."
The cmake documentation (https://cmake.org/cmake/help/v3.5/module/FindPythonLibs.html) says that: "If calling both find_package(PythonInterp) and find_package(PythonLibs), call find_package(PythonInterp) first to get the currently active Python version by default with a consistent version of PYTHON_LIBRARIES."