TLS error from M-x gnus-read-ephemeral-emacs-bug-group

[Glenn Morris]

Just a note to say that the Emacs command gnus-read-ephemeral-emacs-bug-group
now fails with the (old) Emacs 24.3 (the default on fencepost.gnu.org).
It worked fairly recently. It works (on a non-fencepost host) with (eg) 25.1.
This may be https://debbugs.gnu.org/20465, an Emacs problem. Although on
fencepost.gnu.org, it still fails with 25.3. Maybe the gnutls version on
fencepost is old...

Contacting host: debbugs.gnu.org:80
gnutls.c: [0] (Emacs) fatal error: A TLS fatal alert has been received.
gnutls.c: [0] (Emacs) Received alert:  Handshake failed
gnutls.el: (err=[-12] A TLS fatal alert has been received.) boot: (:priority 
NORMAL :hostname debbugs.gnu.org :loglevel 0 :min-prime-bits 256 :trustfiles 
(/etc/ssl/certs/ca-certificates.crt) :crlfiles nil :keylist nil :verify-flags 
nil :verify-error nil :verify-hostname-error nil :callbacks nil)
error in process filter: gnutls-negotiate: GnuTLS error: #<process 
debbugs.gnu.org<1>>, -12
error in process filter: GnuTLS error: #<process debbugs.gnu.org<1>>, -12