bug#51366: Pure storage overflow warning in *GNU Emacs* buffer when emacs@27.2 is invoked

[Calvin Heim]

In emacs@27.2, a warning appears about pure storage overflow in the *GNU Emacs*
buffer that displays at startup. My main concern is that I'm not sure if Emacs's
garbage collection is working or not, so I have been hesitant to upgrade from
version 26.3.

Steps to reproduce (with output):

-----8<---begin-snippet---8<--------------------

$ guix environment -C --pure --preserve=TERM --user=foo --no-cwd --ad-hoc emacs

$ emacs -nw --batch --eval="(progn (display-about-screen)(message \"%s\"
(buffer-substring-no-properties 1 122)))"

Warning Warning!!!  Pure space overflow    !!!Warning Warning
(See the node Pure Storage in the Lisp manual for details.)

-----8<---end-snippet---8<--------------------

I am using Guix on a foreign distribution (Trisquel 9).

$ guix describe
guix 075c9f1
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: 075c9f12696d23bc86999b7a9ed567f38715e00a

The corresponding emacs@27.2 store item is
/gnu/store/n1zvyjk8hm51793ap5ikvzvq15lxkhrg-emacs-27.2

$ uname -i
i686