If you create a VM instance in testcloud, but then delete the VM manually using libvirt (and not testcloud), testcloud is going to complain every time you do testcloud instance list and it will list those VMs as de-sync, e.g.:

WARNING:taskotron-bbb9bcf6-efa9-11e6-97cb-525400cb0b45 is not registered, might want to delete it.

Removing those old VM definitions is hard to manually, especially if there are hundreds of them.

Please introduce a new command testcloud clean de-sync or perhaps testcloud instance clean de-sync that will delete all de-synced VMs using a single command.