Fix abstract filetype not being set for network client join savegames

src/network/network_client.cpp

@@ -1032,6 +1032,10 @@ NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_MAP_DONE(Packet
 
 	/* The map is done downloading, load it */
 	ClearErrorMessages();
+
+	/* Set the abstract filetype. This is read during savegame load. */
+	_file_to_saveload.SetMode(SLO_LOAD, FT_SAVEGAME, DFT_GAME_FILE);
+
 	std::string error_detail;
 	bool load_success = SafeLoad({}, SLO_LOAD, DFT_GAME_FILE, GM_NORMAL, NO_DIRECTORY, std::move(this->savegame), &error_detail);
 	this->savegame = nullptr;