Fix Pcbnew Python: LoadBoard does not rebuild connectivity database, and later, SaveBoard does not save net class memberships

Fixes: lp:1711268
https://bugs.launchpad.net/kicad/+bug/1711268

pcbnew/class_board.cpp

@@ -123,6 +123,12 @@ BOARD::~BOARD()
 }
 
 
+void BOARD::BuildConnectivity()
+{
+    GetConnectivity()->Build( this );
+}
+
+
 const wxPoint& BOARD::GetPosition() const
 {
     wxLogWarning( wxT( "This should not be called on the BOARD object") );

pcbnew/class_board.h

@@ -292,6 +292,14 @@ public:
         return m_connectivity;
     }
 
+    /**
+     * Builds or rebuilds the board connectivity database for the board,
+     * especially the list of connected items, list of nets and rastnest data
+     * Needed after loading a board to have the connectivity database updated.
+     */
+    void BuildConnectivity();
+
+
     /**
      * Function DeleteMARKERs
      * deletes ALL MARKERS from the board.

pcbnew/files.cpp

@@ -579,11 +579,8 @@ bool PCB_EDIT_FRAME::OpenProjectFiles( const std::vector<wxString>& aFileSet, in
     SetCurrentNetClass( NETCLASS::Default );
 
     // Rebuild list of nets (full ratsnest rebuild)
-    {
-        wxBusyCursor dummy;    // Displays an Hourglass while building connectivity
-        Compile_Ratsnest( NULL, true );
-        GetBoard()->GetConnectivity()->Build( GetBoard() );
-    }
+    Compile_Ratsnest( NULL, true );
+    GetBoard()->BuildConnectivity();
 
     // Update info shown by the horizontal toolbars
     ReFillLayerWidget();

pcbnew/python/examples/hidePcbValuesShowReferences.py

@@ -6,9 +6,9 @@ filename=sys.argv[1]
 
 pcb = LoadBoard(filename)
 
-for module in pcb.GetModules():    
+for module in pcb.GetModules():
     print "* Module: %s"%module.GetReference()
     module.Value().SetVisible(False)      # set Value as Hidden
     module.Reference().SetVisible(True)   # set Reference as Visible
-    
-pcb.Save("mod_"+filename)	
+
+SaveBoard("mod_"+filename, pcb)

pcbnew/swig/pcbnew_scripting_helpers.cpp

@@ -72,12 +72,18 @@ BOARD* LoadBoard( wxString& aFileName )
 
 BOARD* LoadBoard( wxString& aFileName, IO_MGR::PCB_FILE_T aFormat )
 {
-    return IO_MGR::Load( aFormat, aFileName );
+    BOARD* brd = IO_MGR::Load( aFormat, aFileName );
+
+    if( brd )
+        brd->BuildConnectivity();
+
+    return brd;
 }
 
 
 bool SaveBoard( wxString& aFileName, BOARD* aBoard, IO_MGR::PCB_FILE_T aFormat )
 {
+    aBoard->BuildConnectivity();
     aBoard->SynchronizeNetsAndNetClasses();
     aBoard->GetDesignSettings().SetCurrentNetClass( NETCLASS::Default );