When QCamera::start() fails error signal is not emitted and the status is wrong

When starting a QCamera instance, which is attached to a physical camera that is already in use, the error() signal is not emitted, the state stays correctly in QCamera::UnloadedState, but the status claims QCamera::LoadedStatus. Also a vague "failed to start" output is printed into debug log (it comes from DSCameraSession::startPreview(), line 542). When QCamera::start() fails we expect to see the error() signal and correct camera status (QCamera::UnavailableStatus maybe).

Tested only on Windows with DirectShow multimedia backend.

The attached simple example reproduces the problem. The state, status and error are printed to debug output.