Add a script to fix population cap problems.

scripts/devel/migrants-now.lua

@@ -0,0 +1,9 @@
+-- Force a migrants event in next 10 ticks.
+
+df.global.timed_events:insert('#',{
+    new = true,
+    type = df.timed_event_type.Migrants,
+    season = df.global.cur_season,
+    season_ticks = df.global.cur_season_tick+1,
+    entity = df.historical_entity.find(df.global.ui.civ_id)
+})

scripts/fix/population-cap.lua

@@ -0,0 +1,40 @@
+-- Communicates current population to mountainhomes to avoid cap overshooting.
+
+-- The reason for population cap problems is that the population value it
+-- is compared against comes from the last dwarven caravan that successfully
+-- left for mountainhomes. This script instantly updates it.
+-- Note that a migration wave can still overshoot the limit by 1-2 dwarves because
+-- of the last migrant bringing his family. Likewise, king arrival ignores cap.
+
+local args = {...}
+
+local ui = df.global.ui
+local ui_stats = ui.tasks
+local civ = df.historical_entity.find(ui.civ_id)
+
+if not civ then
+    qerror('No active fortress.')
+end
+
+local civ_stats = civ.activity_stats
+
+if not civ_stats then
+    if args[1] ~= 'force' then
+        qerror('No caravan report object; use "fix/population-cap force" to create one')
+    end
+    print('Creating an empty statistics structure...')
+    civ.activity_stats = {
+        new = true,
+        created_weapons = { resize = #ui_stats.created_weapons },
+        known_creatures1 = { resize = #ui_stats.known_creatures1 },
+        known_creatures = { resize = #ui_stats.known_creatures },
+        known_plants1 = { resize = #ui_stats.known_plants1 },
+        known_plants = { resize = #ui_stats.known_plants },
+    }
+    civ_stats = civ.activity_stats
+end
+
+-- Use max to keep at least some of the original caravan communication idea
+civ_stats.population = math.max(civ_stats.population, ui_stats.population)
+
+print('Home civ notified about current population.')