Hi Diane,
I asked on the guix help mailing list for you and this is the answer I got
https://lists.gnu.org/archive/html/help-guix/2017-12/msg00097.html
Thank you Konrad !!
@catonano :) Thank you... It mostly mattered because git pull was downloading master.tar.gz, and the VMs guix environment was too old to build it.
@alienghic the right lin is this one
https://lists.gnu.org/archive/html/help-guix/2017-12/msg00101.html