> Inspired by the impending decommissioning of ftp://ftp.gnu.org due to
> security concerns, I went through the Emacs master branch and changed these
> FTP URLs to https://ftp.gnu.org. While I was at it, I did the much-bigger
> task of changing http: to https: for most gnu.org and fsf.org URLs. (I
> ran out of energy before doing the MS-Windows files, and I hope someone
> else can take up the slack there.)
>

Sorry if I'm being dense here, but isn't this simply a matter of running
`sed -i` recursively and changing all the link at once with the appropriate
regex?

Philippe