Which cookie to save to avoid GitHub two-factor authentication?

Question

I've enabled GitHub's two-factor authentication, and I also use the Firefox add-on selectivecookiedelete to delete most cookies upon closing the browser. I would like to white-list GitHub's domain, however, as it's tedious to enter the two-factor authentication code every time I log in.

If I add github.com to the white-list, however, it doesn't work.

Which cookie should I save to stay authenticated on GitHub?

Answer 1

For whatever reason, saving the cookies from github.com now works as you would expect, and I don't have to re-enter a verification code every time I start my browser. I don't know what changed.

Edit: And now the problem is back.