[Bugfix] Cherry pick

python/dune/codegen/sumfact/realization.py

@@ -24,8 +24,7 @@ from dune.codegen.options import (get_form_option,
                                   get_option,
                                   )
 from dune.codegen.pdelab.signatures import assembler_routine_name
-from dune.codegen.sumfact.permutation import (sumfact_permutation_strategy,
-                                              permute_backward,
+from dune.codegen.sumfact.permutation import (permute_backward,
                                               permute_forward,
                                               )
 from dune.codegen.sumfact.quadrature import quadrature_points_per_direction