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.
#if defined(HAVE_CONFIG_H)
#include <config/bitcoin-config.h>
#endif
#include <fs.h>
#include <qt/intro.h>
#include <qt/forms/ui_intro.h>
#include <qt/guiutil.h>
#include <interfaces/node.h>
#include <util.h>
#include <QFileDialog>
#include <QSettings>
#include <QMessageBox>
#include <cmath>
static const uint64_t GB_BYTES = 1000000000LL;
constexpr uint64_t BLOCK_CHAIN_SIZE = 220;
static const uint64_t CHAIN_STATE_SIZE = 3;
static uint64_t requiredSpace;
/* Check free space asynchronously to prevent hanging the UI thread.
   Up to one request to check a path is in flight to this thread; when the check()
   function runs, the current path is requested from the associated Intro object.
   The reply is sent back through a signal.
   This ensures that no queue of checking requests is built up while the user is
   still entering the path, and that always the most recently entered path is checked as
   soon as the thread becomes available.
*/
class FreespaceChecker : public QObject