QGenericUnixServices::openUrl() calls kde-open with the applications LD_LIBRARY_PATH

QGenericUnixServices::openUrl() calls xdg-open.
In a KDE environment this ends up in kde-open, which depends on Qt.
QDesktopServices::openUrl() fails, when

• called from an App that has been compiled against a more recent Qt version than kde-open, and
• the app sets LD_LIBRARY_PATH to point at the (newer) Qt version against which it was built.

The reason is that xdg-open is called by the static QProcess::startDetached(), which inherits the application's process environment. That makes no sense. A desktop service should be called with LD_LIBRARY_PATH unset.

That can be easily reproduced, by adding the following to tst_qdesktopservices::openUrl():

    const QUrl url("https://www.qt.io");
    QCOMPARE(QDesktopServices::openUrl(url), true);

The website will not be launched. Instead, the following error message will appear (on openSuSE 15.6):

kde-open: /home/axel/QtGit/toplevel/build/dev/qtbase/lib/libQt6Gui.so.6: version `Qt_6.8.1_PRIVATE_API' not found (required by /lib64/libKF6WindowSystem.so.6)

The test will pass anyhow, because kde-open will write it to std::err, after QDesktopServices::openUrl() has returned true.