Pad properties dialog needs to edit the local value, not the resultant value.

Fixes: lp:1838618
* https://bugs.launchpad.net/kicad/+bug/1838618

pcbnew/class_pad.h

@@ -506,6 +506,7 @@ public:
 
     void SetZoneConnection( ZoneConnection aType ) { m_ZoneConnection = aType; }
     ZoneConnection GetZoneConnection() const;
+    ZoneConnection GetLocalZoneConnection() const { return m_ZoneConnection; }
 
     void SetThermalWidth( int aWidth ) { m_ThermalWidth = aWidth; }
     int GetThermalWidth() const;

pcbnew/dialogs/dialog_pad_properties.cpp

@@ -669,7 +669,7 @@ void DIALOG_PAD_PROPERTIES::initValues()
     else
         m_SolderPasteMarginRatioCtrl->SetValue( msg );
 
-    switch( m_dummyPad->GetZoneConnection() )
+    switch( m_dummyPad->GetLocalZoneConnection() )
     {
     default:
     case PAD_ZONE_CONN_INHERITED: m_ZoneConnectionChoice->SetSelection( 0 ); break;