0. Stage some sort of failure during TFTP orchestration (maybe set :tftproot to a bad path in the proxy & restart it)
1. Try creating a new host on a compute resource, which should fail due to TFTP orchestration
2. The new host form reappears with the orchestration error
3. Resubmit the form and the VM is no longer created

(another similar scenario in bug #6379)

What appears to happen is that the form reloads, but without the VM tab. Next time the form is submitted, no compute_attributes are sent and so the VM isn't recreated.