Disclaimer: I have not written the code nor do I understand what is trying to achieve. I merely collect the data and report the problems to the package maintainers.

It just seems to me that a non-underscored (and hence public) member variable on a non-underscored (and hence public) structure should not suddenly go missing. Although, I am not familiar with the rules that define what part of the API falls under https://www.python.org/dev/peps/pep-0497/