bug#38940: \x1b]8; ; OSC character displayed on hyperlinks shown after calls to `guix describe` or `guix show` on mate-terminal 1.12.1 (Trisquel 8)

[Calvin Heim <frofroggy@gmail.com>]

Hi Guix developers,

When using mate-terminal version 1.12.1 (the default graphical terminal provided in Trisquel 8), Guix commands
that print hyperlinks to the terminal (such as `guix describe` and `guix show`)
print a mangled \x1b]8;; OSC character. I haven't tested the mate-terminal
package provided by Guix though, so this bug may only be visible to Trisquel users
of the Guix package manager relying on their host distribution's default terminal soon
after installing Guix.

On a related note, the procedure supports-hyperlinks in module (guix ui) checks the
environment variable INSIDE_EMACS to prevent hyperlink mangling when using Emacs.
Perhaps this procedure could be edited to solve this bug.

--
Calvin