ignore hidden edges for bmesh grid-fill.

source/blender/bmesh/operators/bmo_grid_fill.c

@@ -327,6 +327,11 @@ static bool bm_edge_test_cb(BMEdge *e, void *bm_v)
 
 static bool bm_edge_test_rail_cb(BMEdge *e, void *UNUSED(bm_v))
 {
+	/* normally operators dont check for hidden state
+	 * but alternative would be to pass slot of rail edges */
+	if (BM_elem_flag_test(e, BM_ELEM_HIDDEN)) {
+		return false;
+	}
 	return BM_edge_is_wire(e) || BM_edge_is_boundary(e);
 }