In light of Chrome's recent push to mark all HTTP pages insecure (as well as some admonishment from a buddy at work) this site now enforces HTTPS. Github pages added support for HTTPS on custom domains in May, so the only outstanding issue was to have Pelican generate an HTTPS-only version of the site (to prevent mixed content.)
Turns out, doing that is really easy. All you have to do is change your SITEURL from this
SITEURL = 'http://mysite.com'
to this
SITEURL = 'https://mysite.com'
Yup. That s is all it takes. Regenerate, push, and you're good to go!