libvirt provider build failing at post-process step

[mcandre]

Looks like Vagrant has shuffled around how atlas post-processing is setup with qemu:

$ packer build template.json
...
Build 'qemu' errored: 1 error(s) occurred:

* Post-processor failed: Vagrant-related functionality has been removed from Terraform
Enterprise into its own product, Vagrant Cloud. For more information see
https://www.vagrantup.com/docs/vagrant-cloud/vagrant-cloud-migration.html
Please replace the Atlas post-processor with the Vagrant Cloud post-processor,
and see https://www.packer.io/docs/post-processors/vagrant-cloud.html for
more detail.

The VirtualBox build succeeds. The VMware build would probably also succeed if I could summon the funds to buy the latest version.

I'm using packer v1.1.2 by the way. On macOS Sierra.