Python wrapping segfault during build, Ubuntu

I'm seeing a segfault during build of PV master as of 4/7, in the python wrapping tool:

[1775/18990] Generating Python wrapper sources for vtkStructuredAMRNeighbor
FAILED: CMakeFiles/vtkFiltersGeometryPython/vtkStructuredAMRNeighborPython.cxx 
cd /mnt/projects/ParaView/build && /mnt/projects/ParaView/build/bin/vtkWrapPython-pv5.9 @/mnt/projects/ParaView/build/CMakeFiles/vtkFiltersGeometryPython/vtkFiltersGeometry-python.Debug.args -o /mnt/projects/ParaView/build/CMakeFiles/vtkFiltersGeometryPython/vtkStructuredAMRNeighborPython.cxx /mnt/projects/ParaView/src/VTK/Filters/Geometry/vtkStructuredAMRNeighbor.h
Segmentation fault (core dumped)
[1776/18990] Generating Python wrapper sources for vtkProcess
FAILED: CMakeFiles/vtkParallelCorePython/vtkProcessPython.cxx 
cd /mnt/projects/ParaView/build && /mnt/projects/ParaView/build/bin/vtkWrapPython-pv5.9 @/mnt/projects/ParaView/build/CMakeFiles/vtkParallelCorePython/vtkParallelCore-python.Debug.args -o /mnt/projects/ParaView/build/CMakeFiles/vtkParallelCorePython/vtkProcessPython.cxx /mnt/projects/ParaView/src/VTK/Parallel/Core/vtkProcess.h
Segmentation fault (core dumped)
[1781/18990] Generating Python wrapper sources for vtkAbstractGridConnectivity
FAILED: CMakeFiles/vtkFiltersGeometryPython/vtkAbstractGridConnectivityPython.cxx 
cd /mnt/projects/ParaView/build && /mnt/projects/ParaView/build/bin/vtkWrapPython-pv5.9 @/mnt/projects/ParaView/build/CMakeFiles/vtkFiltersGeometryPython/vtkFiltersGeometry-python.Debug.args -o /mnt/projects/ParaView/build/CMakeFiles/vtkFiltersGeometryPython/vtkAbstractGridConnectivityPython.cxx /mnt/projects/ParaView/src/VTK/Filters/Geometry/vtkAbstractGridConnectivity.h

I'm building on Ubuntu 18.04, with system Qt 5.15.2, system installed python 3.8.9, with these options:

# cmake -G Ninja -C ../build.cmake ../src
set(Qt5_DIR "/mnt/projects/Qt/5.15.2/gcc_64/lib/cmake/Qt5" CACHE PATH "")
set(PARAVIEW_USE_PYTHON ON CACHE BOOL "")
set(PARAVIEW_BUILD_TESTING ON CACHE BOOL "")
set(PARAVIEW_BUILD_LEGACY_REMOVE ON CACHE BOOL "")
set(VTK_PYTHON_VERSION "3.8" CACHE STRING "")
set(VTK_PYTHON_OPTIONAL_LINK OFF CACHE BOOL "")

CC @ben.boeckel @dgobbi