ghost keyboard input when focus of window changed in Windows.

Environments:
Windows 10 Enterprise build 19041.1415
Korean language
winit = "0.26.0"

problem:
when I change focus of window, KeyboardInput event is polled.
When losing focus, VirtualKeycode::Kana with scancode 56 has polled.
When gaining focus, two event has polled in a row. scancode 0 was first, VirtualKeycode::Kana with scancode was second.
state of all of them was released.

step to reproduce:

Event::WindowEvent { window_id, event } if window_id == self.window.id() => {
    match event {
        WindowEvent::KeyboardInput { input, .. } => {
        println!("keyboard: {:?}", input);
    }
    _=> {}
}

Start by reproducing the WindowEvent::KeyboardInput behavior on Windows 10 with Korean input and winit 0.26.0, focusing on events emitted when window focus changes. Done means focus changes no longer produce the reported spurious released events, including scancode 0 and VirtualKeycode::Kana.