After guix update new devices appeared in File Manager
Screenshot of Thunar: http://0x0.st/sGkH.png

$ guix describe
Generation 20    Dec 04 2018 17:59:42    (current)
  guix 4ebfe99
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: 4ebfe99a3fc24d7139bd53fab6e1529f5a6d7184

There was only 'File system' link before. How to hide the others?