Expected behaviour

cv2.cvtColor should be able to convert a single pixel's color as it does in version 4.5.3.56

Actual behaviour

Traceback (most recent call last):
  File "raw_tester.py", line 23, in <module>
    npimg = cv2.cvtColor(pixel, cv2.COLOR_RGB2BGR)
cv2.error: OpenCV(4.5.4-dev) D:\a\opencv-python\opencv-python\opencv\modules\core\src\matrix.cpp:466: error: (-215:Assertion failed) _step >= minstep in function 'cv::Mat::Mat'

Steps to reproduce

import cv2
import numpy as np

pixel = np.uint8([[[40, 50, 200]]])
new_pixel = cv2.cvtColor(pixel, cv2.COLOR_RGB2BGR)
print(new_pixel)

• Win10 x64
• opencv-contrib-python-headless 4.5.4.58

Issue submission checklist

• This is not a generic OpenCV usage question (looking for help for coding, other usage questions, homework etc.)
• I have read the README of this repository and understand that this repository provides only an automated build toolchain for OpenCV Python packages (there is no actual OpenCV code here)
• The issue is related to the build scripts in this repository, to the pre-built binaries or is a feature request (such as "please enable this additional dependency")
• I'm using the latest version of opencv-python