[Freeciv-Dev] Core dump in aihand.c

[Jake Kesinger <kesinger@xxxxxxxxxxxx>]

Stack trace is: 
#0  0x807a06c in ai_manage_taxes (pplayer=0x8201ec4) at aihand.c:413
#1  0x807933d in ai_do_last_activities (pplayer=0x8201ec4) at aihand.c:121
#2  0x805a3c7 in update_player_activities (pplayer=0x8201ec4) at plrhand.c:596
#3  0x804f1e8 in end_turn () at civserver.c:689
#4  0x804e7f3 in main (argc=4, argv=0xbffffae4) at civserver.c:428
#5  0x8048f8e in ___crt_dummy__ ()

Line 413 is
          unit_list_iterate(pcity->units_supported, punit)

pcity->units_supported is:

$3 = {list = {nelements = 1, null_link = {next = 0x8218494, prev = 0x8218494,
      dataptr = 0x0}, head_link = 0x821c850, tail_link = 0x821c850}}

and punit is:
$4 = (struct unit *) 0x3


In context:
           if (pcity->shield_surplus < 0) {
             unit_list_iterate(pcity->units_supported, punit)
               if (punit != defender && pcity->shield_surplus < 0) {
                 /* the defender MUST NOT be disbanded! -- Syela */
                 flog(LOG_DEBUG, "Disbanding %s's %s",
                      pcity->name, unit_types[punit->type].name);
                 pack.unit_id = punit->id;
                 handle_unit_disband(pplayer, &pack);
                 city_refresh(pcity);
               }
             unit_list_iterate_end;
           }

The block is only entered if pcity->shield_surplus <0, but at the core dump
pcity->shield_surplus is equal to zero.  

This bug popped up in a 4 AI game in 140AD.

  ==Jake