butterflies: fix generation calculation bug

src/modules/butterflies/butterflies_populations.c

@@ -102,10 +102,14 @@ void bf_cell_maturation(struct cats_grid *grid, struct cats_thread_info *ts, cat
         struct conf_data_butterflies *module_conf = CATS_MODULE_DATA;
         float this_generation_fraction = 1.0f;
         float local_generation = data->generations[row][col];
+        int32_t global_max_generation = module_conf->generations_max;
         int32_t local_max_generation = (int32_t) ceilf(local_generation);
+        int32_t global_current_generation = data->generation_current;
         float current_generation_float = (float) data->generation_current;
 
-        if (current_generation_float == local_generation
+        if (global_current_generation == global_max_generation) {
+                this_generation_fraction = 1.0f;
+        } else if (current_generation_float == local_generation
             || data->generation_current == module_conf->generations_min) {
                 this_generation_fraction = 1.0f;
         } else if (data->generation_current == local_max_generation) {