bug#51454: Progress bar in Org source blocks

[excalamus]

I'm trying to document my work with Guix using Emacs Org. If I run a 
shell/sh/bash source block in org-mode, the result has control characters in it.

To reproduce, open a clean instance of Emacs with emacs -q, switch to the 
scratch buffer and insert:

;; eval this first so that source blocks can run sh
(org-babel-do-load-languages
 'org-babel-load-languages
 '((shell . t)))

#+begin_src sh :results output :session test
guix package -u
#+end_src

#+RESULTS:
: guix package: warning: nothing to do

Switch to org-mode, eval the lisp, and C-c C-c the source block. If your system 
is like mine, you'll see control non-printable characters.

When I check how org sees the shell, I get:

#+begin_src sh :results output :session test
echo $TERM
#+end_src

#+RESULTS:
: dumb

I've tried renaming .bashrc and .bash_profile to .bashrc.old and 
.bash_profile.old, starting a new shell and running through the steps above. 
The result is the same.

Thoughts and suggestions?