Investigate the `-tild_else_case` attribute for a fix without changing `move_to` op

[duzy]

Grammar code:

    auto const tild_once_section_def =
      tild_once_case
      >> tild_else_case
      >> omit[sk[lit("{{") >> '~' >> "end" >> -lit("once") >> "}}"]]
      ;

    auto const tild_else_case_def =
      -(omit[sk[lit("{{") >> '~' >> "else" >> "}}"]]
      >> node_list)
      ;

For details, see boostorg/spirit#533 (comment)