Tried to convert a box of the Discourse forum software. This kind of worked but the resulting libvirt box got a wrong "name", that is the number 0:
$ vagrant mutate http://discourse-vms.s3.amazonaws.com/discourse-1.3.0.box libvirt
Downloading box 0 from http://discourse-vms.s3.amazonaws.com/discourse-1.3.0.box
Extracting box file to a temporary directory.
Converting 0 from virtualbox to libvirt.
(100.00/100%)
Cleaning up temporary files.
$ vagrant box list
0 (libvirt, 0)
Tried to convert a box of the Discourse forum software. This kind of worked but the resulting libvirt box got a wrong "name", that is the number 0: