[REG 5.14] user_prefs.json gets written before profile is ready

#include <QApplication>
#include <QWebEngineProfile>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    app.setOrganizationName("qtbug-test");
    QWebEngineProfile *profile = QWebEngineProfile::defaultProfile();
    profile->setPersistentStoragePath("/tmp/test");
    return 0;
}

[723673:723687:0916/184513.927681:WARNING:important_file_writer.cc(97)] temp file failure: /home/florian/.local/share/qtbug-test/testproj/QtWebEngine/Default/user_prefs.json : could not create temporary file: No such file or directory (2)

#0  QtWebEngineCore::ProfileQt::setupPrefService (this=0x55555629a7d0) at ../profile_qt.cpp:303
#1  0x00007fffe1939ac9 in QtWebEngineCore::ProfileQt::ProfileQt (this=0x55555629a7d0, profileAdapter=0x5555561e2470) at ../profile_qt.cpp:97
#2  0x00007fffe1931fe6 in QtWebEngineCore::ProfileAdapter::ProfileAdapter (this=0x5555561e2470, storageName="Default") at ../profile_adapter.cpp:98
#3  0x00007fffe19c0a75 in QtWebEngineCore::WebEngineContext::createDefaultProfileAdapter (this=0x555555dfa8f0) at ../web_engine_context.cpp:317
#4  0x00007fffe1932993 in QtWebEngineCore::ProfileAdapter::createDefaultProfileAdapter () at ../profile_adapter.cpp:239
#5  0x00007fffeeef3a24 in QWebEngineProfile::defaultProfile () at api/qwebengineprofile.cpp:694

#0  QtWebEngineCore::ProfileQt::setupPrefService (this=0x55555629a7d0) at ../profile_qt.cpp:303
#1  0x00007fffe1932b13 in QtWebEngineCore::ProfileAdapter::setDataPath (this=0x5555561e2470, path="/tmp/qutebrowser-basedir-1gbzmbrp/data/webengine") at ../profile_adapter.cpp:270
#2  0x00007fffeeef3346 in QWebEngineProfile::setPersistentStoragePath (this=0x555556371a20, path="/tmp/qutebrowser-basedir-1gbzmbrp/data/webengine") at api/qwebengineprofile.cpp:390