All branches discard padding from < 3.2 savegames up to MAX_TRADE_ROUTES(_OLD). Master patch also adds better handling of 3.2 savegames: amount of padding is saved to the savegame, and that amount of padding gets discarded. This can be become more important in the future, assuming we increase MAX_TRADE_ROUTES ( #45857 )
Traderoute padding causes "unused entry" warnings while reading savegames.
Probably should implement #45855 first as the saving side change.