apply bbox clipping fix to shield symbolizer as applied to text in 96fff72837 - refs #2049

src/agg/process_shield_symbolizer.cpp

@@ -38,13 +38,14 @@ void  agg_renderer<T>::process(shield_symbolizer const& sym,
                                mapnik::feature_impl & feature,
                                proj_transform const& prj_trans)
 {
+    box2d<double> bb = clipping_extent();
     shield_symbolizer_helper<face_manager<freetype_engine>,
         label_collision_detector4> helper(
             sym, feature, prj_trans,
             width_, height_,
             scale_factor_,
             t_, font_manager_, *detector_,
-            clipping_extent());
+            bb);
 
     text_renderer<T> ren(*current_buffer_,
                          font_manager_,