Python Wrapping fail for Windows

A build on Monday 15 March was Ok, I then checked out a branch for Friday 26 March and this failure appears.

The most recent build also fails.

raceback (most recent call last):
  File "D:\Users\amaclean\Development\src\VTKExamples\VTKKitwareExamples\IO\HDRReader\HDRReader.py", line 3, in <module>
    import vtk
  File "D:\Users\amaclean\Development\Kitware\build\VTK\bin\Lib\site-packages\vtk.py", line 30, in <module>
    all_m = importlib.import_module('vtkmodules.all')
  File "C:\Users\amaclean\Miniconda3\envs\VTK\lib\importlib\__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "D:\Users\amaclean\Development\Kitware\build\VTK\bin\Lib\site-packages\vtkmodules\all.py", line 127, in <module>
    from .util.vtkVariant import *
  File "D:\Users\amaclean\Development\Kitware\build\VTK\bin\Lib\site-packages\vtkmodules\util\vtkVariant.py", line 9, in <module>
    'void' : vtkCommonCore.VTK_VOID,
AttributeError: module 'vtkmodules.vtkCommonCore' has no attribute 'VTK_VOID'