Fedora retirement guidelines

[James Hogarth]

Right now the retirement guidelines state that you should only retire in
branched (prior to freeze) and up to master...

But I just had a user bitten by a change in behaviour between dnf and yum
that was discovered here:
https://bugzilla.redhat.com/show_bug.cgi?id=1096506

This is the bug raised with my package:
https://bugzilla.redhat.com/show_bug.cgi?id=1342249

It seems very unintuitive to the user, and wasn't initially apparent to me
until I look at all open dnf bugs and did a "find on page" for
"obsolete"

For now I've opened a rel-eng ticket to get the letsencrypt packages
properly removed from the F23 repos so that a dnf install letsencrypt, like
F24 behaviour, will install certbot.

I guess the real question is - is the dnf behaviour correct, and if the dnf
behaviour isn't going to change should we allow packagers to retire from a
released branch?