On a different maas server, I am not able to get it to commission. 

 Device:         (*) Specify paths/URLs manually

 Kernel:         tftp://10.245.0.10/ppc64el/ubuntu/amd64/hwe-t/trusty/release/boot-kernel 
 Initrd:           tftp://10.245.0.10/ppc64el/ubuntu/amd64/hwe-t/trusty/release/boot-initrd 
 Device tree:                                                                  
 Boot arguments: nomodeset iscsi_target_name=iqn.2004-05.com.ubuntu:maas:epheme

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2016-03-24 07:04:28+0000 [RemoteOriginReadSession (UDP)] Final ACK received, transfer successful
2016-03-24 07:04:28+0000 [-] (UDP Port 60223 Closed)
2016-03-24 07:04:28+0000 [-] Stopping protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37a5f20200>
2016-03-24 07:04:29+0000 [-] Timed during option negotiation process
2016-03-24 07:04:29+0000 [-] Timed during option negotiation process
2016-03-24 07:04:29+0000 [-] Timed during option negotiation process
2016-03-24 07:04:29+0000 [-] (UDP Port 54560 Closed)
2016-03-24 07:04:29+0000 [-] Stopping protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37a56ed3f8>
2016-03-24 07:04:29+0000 [-] (UDP Port 57487 Closed)
2016-03-24 07:04:29+0000 [-] Stopping protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37a7975488>
2016-03-24 07:04:29+0000 [-] (UDP Port 37997 Closed)
2016-03-24 07:04:29+0000 [-] Stopping protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37a79753b0>
2016-03-24 07:04:30+0000 [TFTP (UDP)] Datagram received from ('10.245.0.237', 36123): <RRQDatagram(filename=/ppc64el/pxelinux.cfg/01-98-be-94-01-0f-4c, mode=octet, options={'tsize': '0'})>
2016-03-24 07:04:30+0000 [TFTP (UDP)] Datagram received from ('10.245.0.237', 36123): <RRQDatagram(filename=/ppc64el/pxelinux.cfg/01-98-be-94-01-0f-4c, mode=octet, options={'tsize': '0'})>
2016-03-24 07:04:30+0000 [HTTPPageGetter,client] RemoteOriginReadSession starting on 49182
2016-03-24 07:04:30+0000 [HTTPPageGetter,client] Starting protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37a79757a0>
2016-03-24 07:04:30+0000 [HTTPPageGetter,client] RemoteOriginReadSession starting on 56952
2016-03-24 07:04:30+0000 [HTTPPageGetter,client] Starting protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37a7964098>
2016-03-24 07:04:30+0000 [RemoteOriginReadSession (UDP)] (UDP Port 56952 Closed)
2016-03-24 07:04:30+0000 [RemoteOriginReadSession (UDP)] Stopping protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37a7964098>
2016-03-24 07:04:30+0000 [RemoteOriginReadSession (UDP)] Final ACK received, transfer successful
2016-03-24 07:04:30+0000 [-] (UDP Port 49182 Closed)
2016-03-24 07:04:30+0000 [-] Stopping protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37a79757a0>
2016-03-24 07:04:31+0000 [-] Unhandled Error
        Traceback (most recent call last):
          File "/usr/lib/python2.7/dist-packages/twisted/application/app.py", line 392, in startReactor
            self.config, oldstdout, oldstderr, self.profiler, reactor)
          File "/usr/lib/python2.7/dist-packages/twisted/application/app.py", line 313, in runReactorWithLogging
            reactor.run()
          File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 1192, in run
            self.mainLoop()
          File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 1201, in mainLoop
            self.runUntilCurrent()
        --- <exception caught here> ---
          File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 824, in runUntilCurrent
            call.func(*call.args, **call.kw)
          File "/usr/lib/python2.7/dist-packages/tftp/util.py", line 80, in _call_and_schedule
            self.callable(*self.callable_args, **self.callable_kwargs)
          File "/usr/lib/python2.7/dist-packages/twisted/internet/udp.py", line 254, in write
            return self.socket.send(datagram)
        exceptions.AttributeError: 'Port' object has no attribute 'socket'

2016-03-24 07:04:40+0000 [TFTP (UDP)] Datagram received from ('10.245.0.237', 53242): <RRQDatagram(filename=/ppc64el/ubuntu/amd64/hwe-t/trusty/release/boot-kernel, mode=octet, options={'tsize': '0'})>
2016-03-24 07:04:40+0000 [TFTP (UDP)] Datagram received from ('10.245.0.237', 49570): <RRQDatagram(filename=/ppc64el/ubuntu/amd64/hwe-t/trusty/release/boot-initrd, mode=octet, options={'tsize': '0'})>
ppc64el/ubuntu/amd64/hwe-t/trusty/release/boot-initrd, mode=octet, options={'tsize': '0'})>
2016-03-24 07:04:40+0000 [TFTP (UDP)] Datagram received from ('10.245.0.237', 53242): <RRQDatagram(filename=/ppc64el/ubuntu/amd64/hwe-t/trusty/release/boot-kernel, mode=octet, options={'tsize': '0'})>
2016-03-24 07:04:40+0000 [TFTP (UDP)] Datagram received from ('10.245.0.237', 49570): <RRQDatagram(filename=/ppc64el/ubuntu/amd64/hwe-t/trusty/release/boot-initrd, mode=octet, options={'tsize': '0'})>
2016-03-24 07:04:40+0000 [HTTPPageGetter,client] RemoteOriginReadSession starting on 55401
2016-03-24 07:04:40+0000 [HTTPPageGetter,client] Starting protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37a797d1b8>
2016-03-24 07:04:40+0000 [HTTPPageGetter,client] RemoteOriginReadSession starting on 52641
2016-03-24 07:04:40+0000 [HTTPPageGetter,client] Starting protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37a7950248>
2016-03-24 07:04:40+0000 [RemoteOriginReadSession (UDP)] (UDP Port 52641 Closed)
2016-03-24 07:04:40+0000 [RemoteOriginReadSession (UDP)] Stopping protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37a7950248>
2016-03-24 07:04:40+0000 [TFTP (UDP)] Datagram received from ('10.245.0.237', 49570): <RRQDatagram(filename=/ppc64el/ubuntu/amd64/hwe-t/trusty/release/boot-initrd, mode=octet, options={'tsize': '0'})>
2016-03-24 07:04:40+0000 [HTTPPageGetter,client] RemoteOriginReadSession starting on 59855
2016-03-24 07:04:40+0000 [HTTPPageGetter,client] Starting protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37b50f0908>
2016-03-24 07:04:40+0000 [HTTPPageGetter,client] RemoteOriginReadSession starting on 54889
2016-03-24 07:04:40+0000 [HTTPPageGetter,client] Starting protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37b5938a28>
2016-03-24 07:04:40+0000 [HTTPPageGetter,client] RemoteOriginReadSession starting on 36038
2016-03-24 07:04:40+0000 [HTTPPageGetter,client] Starting protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37a5fc1b00>
2016-03-24 07:04:40+0000 [RemoteOriginReadSession (UDP)] (UDP Port 54889 Closed)
2016-03-24 07:04:40+0000 [RemoteOriginReadSession (UDP)] Stopping protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37b5938a28>
2016-03-24 07:04:40+0000 [RemoteOriginReadSession (UDP)] (UDP Port 36038 Closed)
2016-03-24 07:04:40+0000 [RemoteOriginReadSession (UDP)] Stopping protocol <tftp.bootstrap.RemoteOriginReadSession instance at 0x7f37a5fc1b00>
2016-03-24 07:04:41+0000 [-] Unhandled Error
        Traceback (most recent call last):
          File "/usr/lib/python2.7/dist-packages/twisted/application/app.py", line 392, in startReactor
            self.config, oldstdout, oldstderr, self.profiler, reactor)
          File "/usr/lib/python2.7/dist-packages/twisted/application/app.py", line 313, in runReactorWithLogging
            reactor.run()
          File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 1192, in run
            self.mainLoop()
          File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 1201, in mainLoop
            self.runUntilCurrent()
        --- <exception caught here> ---
          File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 824, in runUntilCurrent
            call.func(*call.args, **call.kw)
          File "/usr/lib/python2.7/dist-packages/tftp/util.py", line 80, in _call_and_schedule
            self.callable(*self.callable_args, **self.callable_kwargs)
          File "/usr/lib/python2.7/dist-packages/twisted/internet/udp.py", line 254, in write
            return self.socket.send(datagram)
        exceptions.AttributeError: 'Port' object has no attribute 'socket'

2016-03-24 07:04:41+0000 [-] Unhandled Error
        Traceback (most recent call last):
          File "/usr/lib/python2.7/dist-packages/twisted/application/app.py", line 392, in startReactor
            self.config, oldstdout, oldstderr, self.profiler, reactor)
          File "/usr/lib/python2.7/dist-packages/twisted/application/app.py", line 313, in runReactorWithLogging
            reactor.run()
          File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 1192, in run
            self.mainLoop()
          File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 1201, in mainLoop
            self.runUntilCurrent()
        --- <exception caught here> ---
          File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 824, in runUntilCurrent
            call.func(*call.args, **call.kw)
          File "/usr/lib/python2.7/dist-packages/tftp/util.py", line 80, in _call_and_schedule
            self.callable(*self.callable_args, **self.callable_kwargs)
          File "/usr/lib/python2.7/dist-packages/twisted/internet/udp.py", line 254, in write
            return self.socket.send(datagram)
        exceptions.AttributeError: 'Port' object has no attribute 'socket'

2016-03-24 07:04:41+0000 [-] Unhandled Error
        Traceback (most recent call last):
          File "/usr/lib/python2.7/dist-packages/twisted/application/app.py", line 392, in startReactor
            self.config, oldstdout, oldstderr, self.profiler, reactor)
          File "/usr/lib/python2.7/dist-packages/twisted/application/app.py", line 313, in runReactorWithLogging
            reactor.run()
          File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 1192, in run
            self.mainLoop()
          File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 1201, in mainLoop
            self.runUntilCurrent()
        --- <exception caught here> ---
          File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 824, in runUntilCurrent
            call.func(*call.args, **call.kw)
          File "/usr/lib/python2.7/dist-packages/tftp/util.py", line 80, in _call_and_schedule
            self.callable(*self.callable_args, **self.callable_kwargs)
          File "/usr/lib/python2.7/dist-packages/twisted/internet/udp.py", line 254, in write
            return self.socket.send(datagram)
        exceptions.AttributeError: 'Port' object has no attribute 'socket'

2016-03-24 07:04:43+0000 [RemoteOriginReadSession (UDP)] Final ACK received, transfer successful