Subject: bug#31635: mapcon hangs emacs 24.5.1 of debian

From: Dave Goel <[email-masked]>
Date: Mon, 28 May 2018 19:33:04 -0400

(require 'cl)

(mapcon 'identity (list nil nil nil)) => hangs

(emacs-version)

"GNU Emacs 24.5.1 (x86_64-pc-linux-gnu, GTK+ Version 3.22.11)
 of 2017-09-12 on hullmann, modified by Debian"