bug#48300: Guix Emacs does not get "America/Sao_Paulo" timezone by name

[Jorge P. de Morais Neto]

Hi all!  I use Guix on Debian bullseye¹.  My Emacs is a Guix-installed
emacs-next with a package transformation option to use the latest commit
from the master branch.  It works fine except that it wrongly evaluates
the following function call:
    (current-time-zone nil "America/Sao_Paulo")
It returns `(0 "America")'.  And I have verified that the same bug also
occurs on plain Emacs 27.2 (also from Guix).

Last time I tested in a manually compiled Emacs 27.1.50, I got the
correct result: `(-10800 "-03")'.  Also I have just tested on someone
else’s notebook---Emacs 26.3 from Ubuntu---and it too returned the
correct result.  I have not tested other timezones.

Thank you for your work in GNU!

¹ I intend to migrate to PureOS for better free software ethics.

Regards

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