Swept body looks incorrect for this sample

Paste this code to void CModelingDoc::OnWire() and include <BRepOffsetAPI_MakePipeShell.hxx>

TopoDS_Wire profile;

    {
        BRep_Builder builder;
        TopoDS_Vertex verts[4];

        builder.MakeVertex(verts[0], gp_Pnt(-26, 12, 0), Precision::Confusion());
        builder.MakeVertex(verts[1], gp_Pnt(-26, 0, 0), Precision::Confusion());
        builder.MakeVertex(verts[2], gp_Pnt(26, 0, 0), Precision::Confusion());
        builder.MakeVertex(verts[3], gp_Pnt(26, 12, 0), Precision::Confusion());

        BRepBuilderAPI_MakeEdge line1(verts[0], verts[1]);
        BRepBuilderAPI_MakeEdge line2(verts[1], verts[2]);
        BRepBuilderAPI_MakeEdge line3(verts[2], verts[3]);
        BRepBuilderAPI_MakeEdge line4(verts[3], verts[0]);
        BRepBuilderAPI_MakeWire wire_maker;

        wire_maker.Add(line1.Edge());
        wire_maker.Add(line2.Edge());
        wire_maker.Add(line3.Edge());
        wire_maker.Add(line4.Edge());

        profile = wire_maker.Wire();
    }

    TopoDS_Wire path;

    {
        TColStd_Array1OfReal knots(1, 5);
        knots(1) = 0;
        knots(2) = 51.0881590977792043872796;
        knots(3) = 107.168458669019017293067;
        knots(4) = 183.588351367190227847459;
        knots(5) = 226.108934618128841975704;
        TColgp_Array1OfPnt poles(1, 7);
        poles(1) = gp_Pnt(-1, 0, -179);
        poles(2) = gp_Pnt(16.3889401679998876204536, 0, -170.243017571998649373199);
        poles(3) = gp_Pnt(37.082312570477270696756, 0, -141.435758819370448691188);
        poles(4) = gp_Pnt(41.486375303785358426012, 0, -71.1477890837955300185058);
        poles(5) = gp_Pnt(-42.7880805804954960080977, 0, -41.4882630495723816466125);
        poles(6) = gp_Pnt(-22.2735032725623796068248, -0, -12.263785177549062055391);
        poles(7) = gp_Pnt(1, 0, 0);
        TColStd_Array1OfInteger mults(1, 5);
        mults(1) = 4;
        mults(2) = 1;
        mults(3) = 1;
        mults(4) = 1;
        mults(5) = 4;
        bool is_periodic = 0;
        int degree = 3;

        Handle(Geom_BSplineCurve) spl = new Geom_BSplineCurve(poles, knots, mults, degree, is_periodic);
        BRepBuilderAPI_MakeEdge edge_maker(spl);
        BRepBuilderAPI_MakeWire wire_maker;
        TopoDS_Edge edge = edge_maker.Edge();

        edge.Reverse();

        wire_maker.Add(edge);

        path = wire_maker.Wire();
    }

    BRepOffsetAPI_MakePipeShell sweep(path);

    sweep.Add(profile, Standard_False, Standard_False);
    sweep.Build();

    Handle(AIS_Shape) ais_profile = new AIS_Shape(profile);
    myAISContext->SetColor(ais_profile,Quantity_NOC_GREEN,Standard_False);
    myAISContext->Display(ais_profile,Standard_False);

    Handle(AIS_Shape) ais_path = new AIS_Shape(path);
    myAISContext->SetColor(ais_path,Quantity_NOC_GREEN,Standard_False);
    myAISContext->Display(ais_path,Standard_False);

    Handle(AIS_Shape) ais_prism = new AIS_Shape(sweep.Shape());
    myAISContext->SetColor(ais_prism,Quantity_NOC_RED,Standard_False);
    myAISContext->Display(ais_prism,Standard_False);