Bulk commissioning - failure to mount root device from trusty ephemeral image - drops to initramfs shell

I did a bulk commission of 5 nodes, one of the nodes ended up failing to mount /. It dropped to ramfs shell. I checked another node and it was also in ramfs shell. The other 3 nodes never finished commissioning either. This was with maas 1.7.1 RC1 and daily images:

ii maas 1.7.1~rc1+bzr3313-0ubuntu1~trusty1 all MAAS server all-in-one metapackage

This was from the boot console logs:
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Begin: Loading essential drivers[ 49.264063] IPv6: ADDRCONF(NETDEV_UP): eth1: link is not ready
 ... done.
Beg[ 49.351478] e1000: eth1 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
in: Running /scr[ 49.456905] IPv6: ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready
ipts/init-premount ... done.
Begin: Mounting root file system ... Begin: Running /scripts/local-top ... IP-Config: eth1 hardware address 00:22:99:e0:07:76 mtu 1500 DHCP RARP
hostname hayward-52 IP-Config: no response after 2 secs - giving up
IP-Config: eth1 [ 52.255141] Loading iSCSI transport class v2.0-870.
hardware address[ 52.332219] iscsi: registered transport (tcp)
 00:22:99:e0:07:76 mtu 1500 DHCP RARP
hostname hayward-52 hostname hayward-52 IP-Config: eth1 complete (dhcp from 10.245.0.10):
 address: 10.245.38.242 broadcast: 10.245.63.255 netmask: 255.255.192.0
 gateway: 10.245.0.1 dns0 : 10.[ 52.648483] scsi32 : iSCSI Initiator over TCP/IP
245.0.10 dns1 : 0.0.0.0
 domain : oil
 rootserver: 10.245.0.10 rootpath:
 filename : pxelinux.0
iscsistart: Logging into iqn.2004-05.com.ubuntu:maas:ephemeral-ubuntu-amd64-generic-trusty-daily 10.245.0.10:3260,1
iscsistart: version 2.0-873
iscsistart: Connection1:0 to [target: iqn.2004-05.com.ubuntu:maas:ephemeral-ubuntu-amd64-generic-trusty-daily, portal: 10.245.0.10,3260] through [iface: default] is operational now
[ 53.590125] scsi 32:0:0:0: RAID IET Controller 0001 PQ: 0 ANSI: 5
[ 53.688619] scsi 32:0:0:0: Attached scsi generic sg2 type 12
[ 54.510114] scsi 32:0:0:1: Direct-Access IET VIRTUAL-DISK 0001 PQ: 0 ANSI: 5
[ 54.608655] sd 32:0:0:1: Attached scsi generic sg3 type 0
iscsistart: Logging into iqn.2004-05.com.ubuntu:maas:ephemeral-ubuntu-amd64-generic-trusty-daily 10.245.0.10:3260,1
iscsistart: version 2.0-873
iscsistart: initiator reported error (15 - session exists)
done.
[ 55.343087] sd 32:0:0:1: [sdc] 2883584 512-byte logical blocks: (1.47 GB/1.37 GiB)
[ 55.434088] sd 32:0:0:1: [sdc] 4096-byte physical blocks
[ 56.049643] random: nonblocking pool is initialized
[ 56.527787] sd 32:0:0:1: [sdc] Write Protect is on
[ 57.036697] sd 32:0:0:1: [sdc] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 58.445717] sdc: unknown partition table
[ 61.602703] sd 32:0:0:1: [sdc] Attached SCSI disk
Begin: Loading e[ 84.705130] hidraw: raw HID events driver (C) Jiri Kosina
ssential drivers[ 84.781226] usbcore: registered new interface driver usbhid
[ 84.862398] usbhid: USB HID core driver
 ... done.
Begin: Running /scripts/init-premount ... done.
Begin: Mounting root file system ... Begin: Running /scripts/local-top ... IP-Config: eth1 hardware address 00:22:99:e0:07:76 mtu 1500 DHCP RARP
hostname hayward-52 IP-Config: no response after 2 secs - giving up
IP-Config: eth1 hardware address 00:22:99:e0:07:76 mtu 1500 DHCP RARP
hostname hayward-52 hostname hayward-52 IP-Config: eth1 complete (dhcp from 10.245.0.10):
 address: 10.245.38.242 broadcast: 10.245.63.255 netmask: 255.255.192.0
 gateway: 10.245.0.1 dns0 : 10.245.0.10 dns1 : 0.0.0.0
 domain : oil
 rootserver: 10.245.0.10 rootpath:
 filename : pxelinux.0
iscsistart: Logging into iqn.2004-05.com.ubuntu:maas:ephemeral-ubuntu-amd64-generic-trusty-daily 10.245.0.10:3260,1
iscsistart: version 2.0-873
iscsistart: Connection1:0 to [target: iqn.2004-05.com.ubuntu:maas:ephemeral-ubuntu-amd64-generic-trusty-daily, portal: 10.245.0.10,3260] through [iface: default] is operational now
iscsistart: Logging into iqn.2004-05.com.ubuntu:maas:ephemeral-ubuntu-amd64-generic-trusty-daily 10.245.0.10:3260,1
iscsistart: version 2.0-873
iscsistart: initiator reported error (15 - session exists)
done.
Gave up waiting for root device. Common problems:
 - Boot args (cat /proc/cmdline)
   - Check rootdelay= (did the system wait long enough?)
   - Check root= (did the system wait for the right device?)
 - Missing modules (cat /proc/modules; ls /dev)
ALERT! /dev/disk/by-path/ip-10.245.0.10:3260-iscsi-iqn.2004-05.com.ubuntu:maas:ephemeral-ubuntu-amd64-generic-trusty-daily-lun-1 does not exist. Dropping to a shell!

BusyBox v1.21.1 (Ubuntu 1:1.21.0-1ubuntu1) built-in shell (ash)
Enter 'help' for a list of built-in commands.

(initramfs)
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