fix missing return statement

include/boost/range/algorithm_ext/insert.hpp

@@ -39,6 +39,7 @@ inline Container& insert( Container& on, const Range& from )
     BOOST_RANGE_CONCEPT_ASSERT(( ForwardRangeConcept<Container> ));
     BOOST_RANGE_CONCEPT_ASSERT(( SinglePassRangeConcept<Range> ));
     on.insert(boost::begin(from), boost::end(from));
+    return on;
 }
 
     } // namespace range