@when('@:2.4.99')
def patch(self):
    ' see https://github.com/spack/spack/issues/13559 '
    filter_file('import sys', 'import sys; return "{0}"'.format(self.prefix.include), 'pybind11/__init__.py', string=True)
see https://github.com/spack/spack/issues/13559
@when('@:2.4.99')
def patch(self):
    '  '
    filter_file('import sys', 'import sys; return "{0}"'.format(self.prefix.include), 'pybind11/__init__.py', string=True)