Trac #34935: Followup to #34547: fix emacs sage-shell-mode
It turns out that sage-shell-mode in emacs uses the variable
`interfaces`, deleted from `sage.interfaces.all` in #34547. We restore
that variable (which is not used anywhere in the Sage library) along
with a comment.
URL: https://trac.sagemath.org/34935
Reported by: jhpalmieri
Ticket author(s): John Palmieri
Reviewer(s): Matthias Koeppe
Committer
Release Manager
