There was the same problem on both unit_list_sort_ord_city() and unit_list_sort_ord_map(). I noticed the former when I opened this ticket, and the second when I created the patch (patch does not match subject of the ticket). Patch should be updated to cover both functions.
unit_list_sort_ord_city() speaks of server/savegame.c. There's no such file in latest versions, and I'm not sure the functionality referred to was in it even when the file still existed.