Also explode the other bag of holding

src/pickup.c

@@ -2374,6 +2374,8 @@ register struct obj *obj;
         /* did not actually insert obj yet */
         if (was_unpaid)
             addtobill(obj, FALSE, FALSE, TRUE);
+        if (obj->otyp == BAG_OF_HOLDING) /* putting bag of holding into another */
+            do_boh_explosion(obj, (obj->where == OBJ_FLOOR));
         obfree(obj, (struct obj *) 0);
         /* if carried, shop goods will be flagged 'unpaid' and obfree() will
            handle bill issues, but if on floor, we need to put them on bill