Face detection example fails due to incorrect anchor

The face detection example demo_find_face.py
doesn’t seem to work with any version of MaixPy (and the kmodel). It results in the following error message:

ValueError: requested length 8 but object has length 10

It appears this is because the anchor variable is defined as a tuple of 10 elements, while it should have only 8. By simply removing the two last elements, it seems to work.

What is the proper way to fix it?