BOARD_NETLIST_UPDATER: disable auto refill zones if new footprints are loaded and waiting for placement.

Auto refill creates a crash when these footprints are moved, probably due to a partial
connectivity rebuild due to refilling when the connectivity data is not yet finalized.
Fixes #11830
https://gitlab.com/kicad/code/kicad/issues/11830

pcbnew/netlist_reader/board_netlist_updater.cpp

@@ -6,7 +6,7 @@
  * Copyright (C) 2012 SoftPLC Corporation, Dick Hollenbeck <dick@softplc.com>
  * Copyright (C) 2011 Wayne Stambaugh <stambaughw@gmail.com>
  *
- * Copyright (C) 1992-2021 KiCad Developers, see AUTHORS.txt for contributors.
+ * Copyright (C) 1992-2022 KiCad Developers, see AUTHORS.txt for contributors.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -1012,7 +1012,12 @@ bool BOARD_NETLIST_UPDATER::UpdateNetlist( NETLIST& aNetlist )
 
         m_board->GetNetInfo().RemoveUnusedNets();
         m_commit.SetResolveNetConflicts();
-        m_commit.Push( _( "Update netlist" ) );
+
+        // When new footprints are added, the automatic zone refill is disabled because:
+        // * it creates crashes when calculating dynamic ratsnests if auto refill is enabled.
+        // (the auto refills rebuild the connectivity with incomplete data)
+        // * it is useless because zones will be refilled after placing new footprints
+        m_commit.Push( _( "Update netlist" ), m_newFootprintsCount ? ZONE_FILL_OP  : 0 );
 
         m_board->SynchronizeNetsAndNetClasses();
         m_frame->SaveProjectSettings();