From e2db737d1b01327bdb9d3154ce7bfa3331dada34 Mon Sep 17 00:00:00 2001
From: Rasmus Ahlberg <rasmus.ahlberg@electrolux.com>
Date: Mon, 30 Jul 2018 12:15:25 +0200
Subject: [PATCH] Don't copy value if not needed, as source's m_property will
 be set to null when copied.

See https://svn.boost.org/trac10/ticket/13544.
---
 include/boost/graph/detail/adjacency_list.hpp | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/boost/graph/detail/adjacency_list.hpp b/include/boost/graph/detail/adjacency_list.hpp
index 6fb497d7..a8c92df1 100644
--- a/include/boost/graph/detail/adjacency_list.hpp
+++ b/include/boost/graph/detail/adjacency_list.hpp
@@ -2058,13 +2058,17 @@ namespace boost {
       {
         typename EdgeList::iterator ei = el.begin(), e_end = el.end();
         while (ei != e_end) {
-          typename EdgeList::value_type ce = *ei;
-          ++ei;
-          if (ce.get_target() > u) {
+          if (ei->get_target() > u) {
+            typename EdgeList::value_type ce = *ei;
+            ++ei;
             el.erase(ce);
             --ce.get_target();
             el.insert(ce);
           }
+          else
+          {
+            ++ei;
+          }
         }
       }
     } // namespace detail