WMayer's fix: subshape copy

The subshape is copied to prevent the wire tool from modifying it. This
lets the user modify any supporting Bezier curves and the Bezier surface
will follow them.

src/Mod/Surface/App/FeatureBezSurf.cpp

@@ -23,6 +23,7 @@
 
 #include "PreCompiled.h"
 #ifndef _PreComp_
+#include <BRepBuilderAPI_Copy.hxx>
 #include <BRepBuilderAPI_MakeFace.hxx>
 #include <TopoDS.hxx>
 #include <TopoDS_Face.hxx>
@@ -173,6 +174,9 @@ void getCurves(GeomFill_BezierCurves& aBuilder,TopoDS_Wire& aWire, const App::Pr
                
             //we want only the subshape which is linked
             sub = ts.getSubShape(set.sub);
+            // make a copy of the shape and the underlying geometry to avoid to affect the input shapes
+            BRepBuilderAPI_Copy copy(sub);
+            sub = copy.Shape();
             
             if(sub.ShapeType() == TopAbs_EDGE) {  //Check Shape type and assign edge
                 etmp = TopoDS::Edge(sub);