The recent changes to improve protocol security on GitHub.com are now coming to GitHub Enterprise Server, starting with version 3.6.
GitHub Pages will upgrade to the soon-to-be-released Jekyll 3.1.4 on May 23rd. The Jekyll 3.1.x branch brings significant performance improvements to the build process, adds a handful of helpful Liquid filters, and fixes a few minor bugs.
This should be a seamless transition for all GitHub Pages users, but if you have a particularly complex Jekyll site, we recommend building your site locally with the latest version of Jekyll 3.1.x prior to May 18th to ensure your site continues to build as expected.
Edit: To ensure a smooth transition for users, the upgrade has been rescheduled to May 23rd.