bug#39843: Can't open files through file managers in other DEs and WMs

[sirgazil]

After removing the workaround from my system configuration file and 
reconfiguring the system with a recent Guix (see below), things work find in 
MATE, Xfce and sway. I can't reproduce the problems anymore.

$ guix describe
Generation 72   Apr 17 2020 08:12:14    (current)
  sirgazil-x 66d4b67
    repository URL: https://gitlab.com/sirgazil/guix-channel-x.git
    branch: master
    commit: 66d4b677875c84d0b7a946376cd4885f202094eb
  guix 79ef072
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: 79ef0726a9afb7bd4676b9a53401f742c7b83653


Thanks for fixing this.