[2.5] Adding a machine with the non-PXE mac doesn't commission

I added a machine over the UI with:

1. A non-PXE MAC address of the machine.
2. BMC - Manual

The machine was set to 'Commissioning' in MAAS and the machine correctly PXE booted into the enlistment environment:

 1. It tried to enlist itself.
 2. The machine failed to enlist
 3. The machine rebooted

The expectation was:

 1. The machine boot into ephemeral env.
 2. The machine attempts to register itself to MAAS, but since there's already one with the same MAC, it continues:
 3. The machine is told to commission
 4. The machine is marked ready.

In other words, the expectation was that this would work similarly to how BMC Enlistment works, but instead of using the BMC, we would use MAC addresses to identify machines.