bug#61201: Installation hint crashes when user names contain at sign

["Ludovic Courtès" <ludo@gnu.org>]

Ludovic Courtès <ludovic.courtes@inria.fr> skribis:

> A funny thing was reported earlier today on the Café Guix channel:
>
> $ guix install hello  [17:52]
> building profile with 5 packages...
> hint: Backtrace:

[...]

> In guix/ui.scm:
>     312:5  6 (display-hint _ )
>   1451:24  5 (texi->plain-text )
> In texinfo.scm:
>   1132:22  4 (parse )
>    980:31  3 (loop #<input: string 2b6e5926be70> (fragment) _ _ )
>    967:36  2 (loop #<input: string 2b6e5926be70> #f # ?)
>      92:2  1 (command-spec )
> In ice-9/boot-9.scm:
>   1685:16  0 (raise-exception _ #:continuable? )
>  
> ice-9/boot-9.scm:1685:16: In procedure raise-exception:
> Throw to key #E1E1E1">parser-error' with args(#f "Unknown command" univ)'.

Here’s one way to reproduce the bug, showing a crash in ‘display-hint’
due to an unescaped brace:

--8<---------------cut here---------------start------------->8---
$ mkdir /tmp/x{ample
$ touch /tmp/x{ample/guix.scm
$ (cd '/tmp/x{ample' ; guix shell)
guix shell: error: not loading '/tmp/x{ample/guix.scm' because not authorized to do so
hint: Backtrace:
          13 (primitive-load "/home/ludo/.config/guix/current/bin/guix")
In guix/ui.scm:
   2279:7 12 (run-guix . _)
  2242:10 11 (run-guix-command _ . _)
In ice-9/boot-9.scm:
  1752:10 10 (with-exception-handler _ _ #:unwind? _ #:unwind-for-type _)
In guix/scripts/shell.scm:
   308:15  9 (_)
In guix/ui.scm:
    312:5  8 (display-hint _ _)
  1451:24  7 (texi->plain-text _)
In texinfo.scm:
  1132:22  6 (parse _)
   980:31  5 (loop #<input: string 7feb8b300d20> (*fragment*) _ _ _)
   980:31  4 (loop #<input: string 7feb8b300d20> #f _ _ _)
   911:31  3 (loop #<input: string 7feb8b300d20> #f #<procedure identity (x)> #f _)
   746:27  2 (_ #<input: string 7feb8b300d20> #f (example smallexample verbatim lisp smalllisp menu w %) #<procedure 7feb9aea1948 at texin…> …)
In sxml/ssax/input-parse.scm:
     88:2  1 (next-token _ _ _ _)
In ice-9/boot-9.scm:
  1685:16  0 (raise-exception _ #:continuable? _)

ice-9/boot-9.scm:1685:16: In procedure raise-exception:
Throw to key `parser-error' with args `(#<input: string 7feb8b300d20> "EOF while reading a token " "reading char data")'.
--8<---------------cut here---------------end--------------->8---

Ludo’.