Per kenzo of #emacs, bug also exists in build 27 on a mac On Mon, May 28, 2018 at 7:33 PM, Dave Goel wrote: > (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" > > > >