static void _fixup_duplicate_stairs()

static bool _fixup_duplicate_stairs(bool preserve_vault_stairs)

    bool success = true;

        // In Zot, don't create extra escape hatches, in order to force
        // the player through vaults that use all three down stone stairs.
        if (player_in_branch(BRANCH_HALL_OF_ZOT))
            replace = DNGN_GRANITE_STATUE;

                    if (preserve_vault_stairs &&
                        (dgn_Map_Mask(stair_list[s2]) & MMT_VAULT))
                    {
                        continue;
                    }

                if (preserve_vault_stairs)
                {
                    int start = remove;
                    do
                    { 
                        if (!(dgn_Map_Mask(stair_list[remove]) & MMT_VAULT))
                            break;
                        remove = (remove + 1) % num_stairs;
                    }
                    while (start != remove);
                    // If we looped through all possibilities, then it
                    // means that there are more than 3 stairs in vaults and
                    // we can't preserve vault stairs.
                    if (start == remove)
                        break;
                }

        }
        if (num_stairs > 3 && preserve_vault_stairs)
        {
            success = false;
            continue;

    return success;

    _fixup_duplicate_stairs();

    if (!_fixup_duplicate_stairs(true))
    {
#ifdef DEBUG_DIAGNOSTICS
        mprf(MSGCH_DIAGNOSTICS, "Warning: failed to preserve vault stairs.");
#endif
        _fixup_duplicate_stairs(false);
    }