Using a Bitcoin-Qt v0.16.0 ([downloaded from bitcoin page](https://bitcoin.org/bin/bitcoin-core-0.16.0/bitcoin-0.16.0-osx.dmg)) in an macOS High Sierra 10.13.4 

When I start after a fresh install Bitcoin-Qt as a mainnet node and wallet, the wallet prompt that about 203gb is going to be used in my disk
![image](https://user-images.githubusercontent.com/20187136/39899688-ba820bfe-5493-11e8-87d9-460ed5716a02.png)

When I start the node and wallet as testnet, shows the same message about the 203gb disk usage
![image](https://user-images.githubusercontent.com/20187136/39899756-17b31214-5494-11e8-8a57-60e604e74afb.png)

It seems that the second time the message is wrong, due that the testnet database uses about 14gb.
pchMessageStart[3] = 0xd9;
        nDefaultPort = 8333;
        nPruneAfterHeight = 100000;
        genesis = CreateGenesisBlock(1231006505, 2083236893, 0x1d00ffff, 1, 50 * COIN);
        consensus.hashGenesisBlock = genesis.GetHash();
        assert(consensus.hashGenesisBlock == uint256S("0x000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f"));
        assert(genesis.hashMerkleRoot == uint256S("0x4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b"));
        
        
        
        
        
        vSeeds.emplace_back("seed.bitcoin.sipa.be"); 
        vSeeds.emplace_back("dnsseed.bluematt.me"); 
        vSeeds.emplace_back("dnsseed.bitcoin.dashjr.org"); 
        vSeeds.emplace_back("seed.bitcoinstats.com"); 
        vSeeds.emplace_back("seed.bitcoin.jonasschnelli.ch"); 
        vSeeds.emplace_back("seed.btc.petertodd.org"); 
        vSeeds.emplace_back("seed.bitcoin.sprovoost.nl"); 
        base58Prefixes[PUBKEY_ADDRESS] = std::vector<unsigned char>(1,0);
        base58Prefixes[SCRIPT_ADDRESS] = std::vector<unsigned char>(1,5);
        base58Prefixes[SECRET_KEY] =     std::vector<unsigned char>(1,128);
        base58Prefixes[EXT_PUBLIC_KEY] = {0x04, 0x88, 0xB2, 0x1E};
        base58Prefixes[EXT_SECRET_KEY] = {0x04, 0x88, 0xAD, 0xE4};
        bech32_hrp = "bc";
        vFixedSeeds = std::vector<SeedSpec6>(pnSeed6_main, pnSeed6_main + ARRAYLEN(pnSeed6_main));
        fDefaultConsistencyChecks = false;
        fRequireStandard = true;
        fMineBlocksOnDemand = false;
        checkpointData = {