From 683e6dff94fe8c41a1e7f49ad1d2570a0d5f963f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Loriot?= <sebastien.loriot@cgal.org>
Date: Tue, 7 Jun 2016 10:02:00 +0200
Subject: [PATCH] handle isolated vertices in change_orientation

---
 Nef_3/include/CGAL/Nef_polyhedron_3.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Nef_3/include/CGAL/Nef_polyhedron_3.h b/Nef_3/include/CGAL/Nef_polyhedron_3.h
index b6f5b2d79aa..7ee01d0d8ad 100644
--- a/Nef_3/include/CGAL/Nef_polyhedron_3.h
+++ b/Nef_3/include/CGAL/Nef_polyhedron_3.h
@@ -1582,7 +1582,8 @@ protected:
 
    SVertex_iterator sv;
    CGAL_forall_svertices(sv, snc()) {
-     sv->out_sedge() = sv->out_sedge()->twin();
+     if (!sv->is_isolated())
+      sv->out_sedge() = sv->out_sedge()->twin();
    }
 
    SHalfedge_iterator se;