bug#60363: Texlive importer is broken

[Elias Kueny]

Hello,

The texlive importer doesn't return any package definition anymore, for example:

> guix import texlive siunitx
> command "svn" "export" "--non-interactive" "--trust-server-cert" "-r" "59745" 
> "svn://www.tug.org/texlive/tags/texlive-2021.3/Master/texmf-dist/doc/latex/siunitx/" "/tmp/guix-directory.Gs0bAp/doc/latex/siunitx/" failed 
> with signal 11
> guix import: error: failed to download description for package 'siunitx'

I updated guix today (from 0afe9f36d8b8b69d3e69fc8c06aeadc1bd95eecd to 
8f93a1e01a879ae026678dd92c18e2a2a49be540) but since I don't see any recent 
change in guix/import/texlive.scm, I don't know if it's relevant. Other 
importers work fine. All else I can say is that running the same command 
manually works:

> svn export --non-interactive --trust-server-cert -r 59745 
> "svn://tug.org/texlive/tags/texlive-2021.3/Master/texmf-dist/doc/latex/siunitx" 
> "/tmp/guix-directory.Gs0bAp/doc/latex/siunitx/"
> A    siunitx
> A    siunitx/README.md
> A    siunitx/siunitx.pdf
> Exported revision 59745.