Back in August we reported that even invalid HTTPS pages will still get the Google HTTPS ranking boost - all it needs to get it is be on an HTTPS URL.
In October, we reported that Google was working on validating HTTPS and then in November, Google began sending out certificate issue notices via the Google Search Console.
Some people think that invalid HTTPS implementations now will result in you not getting that ranking boost. That is incorrect, at least to date.
Gary Illyes from Google confirmed on Twitter that they still do get the ranking boost. He said, nothing changed with that:
@rustybrick yes, if the URL made it to serving with broken https implementation, it will get a boost. Nothing changed there @oozn @JohnMu
— Gary Illyes (@methode) January 6, 2016
When it does change, and I think it will eventually change, we will let you know.
Forum discussion at Twitter.