Initialize a variable outside the loop where it is incremented.

This should allow the intended limitation of at most two spawns after
$final_turns.

data/multiplayer/scenarios/2p_Dark_Forecast.cfg

@@ -570,13 +570,13 @@ Note: You need to use the default map settings for the scenario to work right."
     # reduce gold and units for spawns
     # after the final spawn
     {VARIABLE spawn_id 0}
+    {VARIABLE end_spawn 0}
     [while]
         [variable]
             name=spawn_id
             less_than=$main_group
         [/variable]
         [do]
-            {VARIABLE end_spawn 0}
             [if]
                 [variable]
                     name=timed_spawn[$spawn_id].turn