Previously, it printed how many were selected, which can include old
members of the group.
(flee, army): The rather obscure feature to assign the fleet's /
army's retreat orders to members was broken. It ignored ownership,
and thus could copy some other player's retreat orders. Abusable.
Copying the first member's retreat orders is less than useful, in
particular for group ~. The code now chooses the first one in the
same sector with RET_GROUP set. RET_GROUP is never set for group ~.
