QTemporaryDir does not work as expected on Windows 10

QString path = QDir::tempPath() + "/" + "QtCreator" + "-XXXXXX";
QTemporaryDir dir(path);
qDebug() << path << dir.path();

path is: "C:/Users/Thomas/AppData/Local/Temp/QtCreator-XXXXXX"
dir.path is : ""

I found this when building Qt Creator with Qt 5.9.2.

With Qt 5.10 (RC) I get the expected result.