Fixing DNS for a Gandi subdomain when using Github Pages
When trying to point a subdomain to Github Pages from a Gandi DNS, I managed to get the domain working but Pages wouldn't allow me to enable the SSL option. When using the Github assistant to troubleshoot the issue it told me that an A record existed, when in fact I had only added a CNAME record.
After some searching I found this gist which proved to be the answer — the default Gandi live DNS includes some items that need to be deleted before Github Pages will be able to use SSL.