Fix some stale pointers in incremental updates

Shared pointers contained stale references to the temporary graph.  When
merging, we need to ensure all references are updated to the final graph

eeschema/connection_graph.cpp

@@ -521,7 +521,12 @@ void CONNECTION_GRAPH::Merge( CONNECTION_GRAPH& aGraph )
             std::back_inserter( m_subgraphs ) );
 
     for( CONNECTION_SUBGRAPH* sg : aGraph.m_subgraphs )
+    {
+        if( sg->m_driver_connection )
+            sg->m_driver_connection->SetGraph( this );
+
         sg->m_graph = this;
+    }
 
     std::copy( aGraph.m_driver_subgraphs.begin(),
             aGraph.m_driver_subgraphs.end(),
@@ -558,6 +563,7 @@ void CONNECTION_GRAPH::Merge( CONNECTION_GRAPH& aGraph )
     m_last_bus_code = std::max( m_last_bus_code, aGraph.m_last_bus_code );
     m_last_net_code = std::max( m_last_net_code, aGraph.m_last_net_code );
     m_last_subgraph_code = std::max( m_last_subgraph_code, aGraph.m_last_subgraph_code );
+
 }
 
 
@@ -775,23 +781,23 @@ void CONNECTION_GRAPH::removeSubgraphs( std::set<CONNECTION_SUBGRAPH*>& aSubgrap
         {
             auto it = std::lower_bound( m_driver_subgraphs.begin(), m_driver_subgraphs.end(), sg );
 
-            if( it != m_driver_subgraphs.end() )
-                m_driver_subgraphs.erase( it );
+            while( it != m_driver_subgraphs.end() && *it == sg )
+                it = m_driver_subgraphs.erase( it );
         }
 
         {
             auto it = std::lower_bound( m_subgraphs.begin(), m_subgraphs.end(), sg );
 
-            if( it != m_subgraphs.end() )
-                m_subgraphs.erase( it );
+            while( it != m_subgraphs.end() && *it == sg )
+                it = m_subgraphs.erase( it );
         }
 
         for( auto& el : m_sheet_to_subgraphs_map )
         {
             auto it = std::lower_bound( el.second.begin(), el.second.end(), sg );
 
-            if( it != el.second.end() )
-                el.second.erase( it );
+            while( it != el.second.end() && *it == sg )
+                it = el.second.erase( it );
         }
 
         auto remove_sg = [sg]( auto it ) -> bool
@@ -870,6 +876,7 @@ void CONNECTION_GRAPH::removeSubgraphs( std::set<CONNECTION_SUBGRAPH*>& aSubgrap
     for( CONNECTION_SUBGRAPH* sg : aSubgraphs )
     {
         sg->m_code = -1;
+        sg->m_graph = nullptr;
         delete sg;
     }
 }

eeschema/sch_item.cpp

@@ -170,7 +170,12 @@ SCH_CONNECTION* SCH_ITEM::Connection( const SCH_SHEET_PATH* aSheet ) const
 void SCH_ITEM::SetConnectionGraph( CONNECTION_GRAPH* aGraph )
 {
     for( auto& [path, conn] : m_connection_map )
+    {
         conn->SetGraph( aGraph );
+
+        for( auto& member : conn->AllMembers() )
+            member->SetGraph( aGraph );
+    }
 }