The HackerNews repo is gone (and thus the issue), but at one point this was a Github issue I successfully filed to get HN to add it so their referral data for non-SSL pages wouldn't be lost:

https://github.com/HackerNews/HN/issues/68

(Background: https://news.ycombinator.com/item?id=7197520)

IIRC, I think the developer was open to adding a referral, but not have it leak any on-site information, so this was a compromise.