Failed build opencv-python without ffmpeg option in Windows

[ioctl-user]

I'm trying build minimal OpenCV-python for Windows for my project, without not needed functions. In my case I don't need video encoding and decoding functions. Also I would like to minimize LGPL libs presence.

At that setup.py contains the following lines:

    rearrange_cmake_output_data = {
        "cv2": (
            [r"bin/opencv_videoio_ffmpeg\d{4}%s\.dll" % ("_64" if is64 else "")]
            if os.name == "nt"
            else []
        )
        +

Here is expected, that ffmpeg dll will be built and packaged. However, there is no such file in case of building without FFMPEG (with CMAKE_ARGS="-DWITH_FFMPEG=OFF" env variable set). These lines leads to build fail in such configuration.

I have changed these lines to fix problem in my case. However, it seems disabling FFMPEG is a common need given the considerations above. Build should not fail in this case.