title: OpenCV Stitcher class not working in Python, always returns ERR_NEED_MORE_IMGS
body: <p>I'm trying to use the OpenCV Stitcher class for putting two images together. I ran the simple example provided in the answer to this <a href="https://stackoverflow.com/questions/34362922/how-to-use-opencv-stitcher-class-with-python">question</a> with the same koala images, but it returns <code>(1, None)</code> every time. I've tried this on opencv-python version 3.4, 4.2, and 4.4, and all have the same result.</p>
  <p>I've tried replacing the stitcher initializer with something else, (<code>cv2.Stitcher.create</code>, <code>cv2.Stitcher_create</code>, <code>cv2.createStitcher</code>), but nothing seems to work. If it helps, I'm on Mac Catalina, using Python 3.7. Thanks!</p>