Megastore errors on save load

[RDru]

Describe the bug

Updating from 9777 to 9778 or later, loading a save causes this errors:

DEBUG    : JSON contains circular dependency. Discarded 2 objects:
{
    "type": "overmap_terrain",
    "id": "megastore_entrance",
    "copy-from": "megastore_entrance",
    "name": "megastore",
    "sym": "M",
    "color": "i_magenta"
  },{
    "type": "overmap_terrain",
    "id": "megastore",
    "copy-from": "megastore",
    "name": "megastore",
    "sym": "m",
    "color": "i_magenta"
  },

 FUNCTION : void DynamicDataLoader::load_deferred(DynamicDataLoader::deferred_json&)
 FILE     : src/init.cpp
 LINE     : 133

DEBUG    : Loaded bad ter! ter megastore

 FUNCTION : void overmap::unserialize(std::istream&)
 FILE     : src/savegame.cpp
 LINE     : 873

Also the megastore on map becomes abandoned drive through.

Steps To Reproduce

Steps to reproduce the behavior:

1. load a save from 9775 or before on 9778 or later with megastore on map.

Expected behavior

Stuff works.

Screenshots

Versions and configuration

Additional context

My save

[ZhilkinSerg]

Duplicate of #34860