adjust price of vermin swarms

docs/changelog.txt

@@ -58,6 +58,7 @@ Template for new versions:
 
 ## Fixes
 - `stockpiles`: hide configure and help buttons when the overlay panel is minimized
+- `caravan`: price of vermin swarms correctly adjusted down. a stack of 10000 is worth 1, not 10000
 
 ## Misc Improvements
 - `buildingplan`: display how many items are available on the planner panel

library/modules/Items.cpp

@@ -2042,8 +2042,12 @@ int Items::getValue(df::item *item, df::caravan_state *caravan)
     {
         int divisor = 1;
         auto creature = vector_get(world->raws.creatures.all, mat_type);
-        if (creature && size_t(mat_subtype) < creature->caste.size())
+        if (creature) {
+            if (creature->flags.is_set(df::creature_raw_flags::VERMIN_SOIL_COLONY))
+                divisor = 10000;
+            else if (size_t(mat_subtype) < creature->caste.size())
                 divisor = creature->caste[mat_subtype]->misc.petvalue_divisor;
+        }
         if (divisor > 1)
             value /= divisor;
     }