[2.3] API allows "deploying" a machine that's already deployed

[Andres Rodriguez]

I had a machine that was in "Deployed" and then I attempted to deploy it via the API by mistake:

ubuntu@maas00:~$ sudo maas admin machine deploy rp86gd install_rackd=True
Success.
Machine-readable output follows:
{
    "hwe_kernel": "ga-16.04",
    "volume_groups": [],
    "special_filesystems": [],
    "disable_ipv4": false,
    "architecture": "amd64/generic",
    "boot_disk": {
        "used_for": "GPT partitioned with 2 partitions",
[...]

But when I try to release it, there's a power action in progress