When AI cannot grow due to aqueduct size limit and already has full foodbox,
prefer shield production over food production that would make no difference whatsoever.

Patch by Emmet Hikory <persia>

See patch #3697


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24752 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Use present = FALSE requirements instead of nreqs vector in civ1 ruleset
effects.ruleset.

See patch #4632


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24753 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Fix crash in is_my_zoc() associated with unknown terrain.

Report and patch by pepeto (pepeto@gna).

See gna bug #21894.

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24754 a0f10bec-cc02-0410-94fc-a9cfff90b4cd