VTK linking to wrong GDAL library (Ubuntu)

This problem showed up on Ubuntu with a completely clean rebuild of latest cmb-superbuild:master and smtk:master (19-Feb-2021). The superbuild finishes ok, but SMTK fails to build any executables because vtkIO is linked to /usr/lib/libgdal.so instead the superbuild's gdal. Grepping paraview's CMakeCache, I can see GDAL_ROOT is set ok but GDAL_LIBRARY is not:

//Path to the GDAL library
GDAL_LIBRARY:FILEPATH=/usr/lib/libgdal.so
GDAL_ROOT:PATH=/home/john/projects/cmb-master/build/dev-superbuild/install

This presumably is not a problem on Centos otherwise CI wouldn't work. Also FWIW I am using cmake 3.19.1