[Freeciv-Dev] (PR#4260) get_defender bug

["Mike Kaufman" <kaufman@xxxxxxxxxxxxxxxxxxxxxx>]

using the civgame+0400.sav.gz game generated by the script in 4259
we get this:

1: get_defender bug: Gro Harlem Brundtland's Archers vs Tassilo III's
Archers (total 4 units) on Ocean at (9,36). 
> civserver: combat.c:514: get_defender: Assertion `0' failed.
Aborted (core dumped)

#0  0x400e3021 in __kill () at __kill:-1
#1  0x400e2ca8 in raise (sig=1075741620) at ../sysdeps/posix/raise.c:27
#2  0x400e456c in *__GI_abort () at ../sysdeps/generic/abort.c:88
#3  0x400dc01a in *__GI___assert_fail (assertion=0x0, file=0x0, line=0, 
    function=0x80f0489 "get_defender") at assert.c:83
#4  0x080a197b in get_defender (attacker=0x8687738, x=9, y=36) at
combat.c:514
#5  0x080d003f in find_something_to_kill (pplayer=0x817e088,
punit=0x8687738, 
    x=0xbffffb54, y=0xbffffb58) at aiunit.c:2229
#6  0x080d0cde in ai_military_attack (pplayer=0x817e088, punit=0x8687738)
    at aiunit.c:2361
#7  0x080d1b4a in ai_manage_military (pplayer=0x817e088, punit=0x8687738)
    at aiunit.c:2758
#8  0x080d209e in ai_manage_units (pplayer=0x817e088) at aiunit.c:2897
#9  0x0804e1f9 in ai_start_turn () at srv_main.c:432
#10 0x0804fb83 in main_loop () at srv_main.c:1428
#11 0x0804fdf5 in srv_main () at srv_main.c:1574
#12 0x0804a058 in main (argc=135245088, argv=0xbffffcb4) at civserver.c:154
#13 0x400cefa4 in __libc_start_main (main=0x8049cc0 <main>, argc=3, 
    ubp_av=0xbffffcb4, init=0x804958c <_init>, fini=0x40015640
<_rtld_local>, 
    rtld_fini=0x6, stack_end=0x401e83b4) at
../sysdeps/generic/libc-start.c:144

-mike