From c268bb2fd40e4036a09bfaee6597975d2b6099f1 Mon Sep 17 00:00:00 2001
From: Barend Gehrels <barend@xs4all.nl>
Date: Sun, 10 Jan 2016 19:14:31 +0100
Subject: [PATCH] Minor change, check on cluster ids

---
 .../algorithms/detail/overlay/handle_colocations.hpp      | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/boost/geometry/algorithms/detail/overlay/handle_colocations.hpp b/include/boost/geometry/algorithms/detail/overlay/handle_colocations.hpp
index 7e07fa1e8..4b84f2ae4 100644
--- a/include/boost/geometry/algorithms/detail/overlay/handle_colocations.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/handle_colocations.hpp
@@ -602,9 +602,13 @@ inline void assign_startable_in_clusters(Clusters& clusters, Turns& turns,
     for (typename Clusters::iterator mit = clusters.begin();
          mit != clusters.end(); ++mit)
     {
-        sbs_type sbs;
-
         std::set<signed_size_type> const& ids = mit->second;
+        if (ids.empty())
+        {
+            continue;
+        }
+
+        sbs_type sbs;
         point_type turn_point; // should be all the same for all turns in cluster
 
         bool first = true;