bug#41811: `guix search` shows control sequences

[Lars-Dominik Braun]

Hi,

when using `guix search python2-xcffib` on a foreign distribution (Gentoo) not
all control sequences are stripped by the pager (see location and license):

---snip---
name: python2-xcffib
version: 0.6.0
outputs: out
systems: x86_64-linux i686-linux
dependencies: libxcb@1.14 python2-cffi@1.13.2 python2-six@1.14.0
location: 
8;;file://xxx/gnu/store/1ccswh99papcvkj028s9myy8kq26y26g-guix-module-union/share/guile/site/3.0/gnu/packages/python-xyz.scmgnu/packages/python-xyz.scm:5437:28;;
homepage: https://github.com/tych0/xcffib
license: 8;;http://directory.fsf.org/wiki/License:ExpatExpat8;;
synopsis: XCB Python bindings
description: Xcffib is a replacement for xpyb, an XCB Python bindings.
It adds support for Python 3 and PyPy.  It is based on cffi.
relevance: 20
---

`guix search python2-xcffib | less` works fine, `unset`ting the environment
variable $LESS or setting it to 'FrX' (i.e. what guix does when it’s missing)
fixes the issue too, so I’m a little puzzled. Some more information:

---snip---
$ env | grep -i less
LESS=-R -M --shift 5
LESSOPEN=|lesspipe %s
PAGER=/usr/bin/less
$ less --version
less 551 (PCRE2 regular expressions)
[…]
$ LANG=C guix describe
Generation 15   Jun 11 2020 17:47:13    (current)
  guix cbd9581
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: cbd9581acc41cd49eb81c2432452cad4de805cbd
---snap---

Cheers,
Lars