Comment 4 for bug 1503179

I have evidence of this occurring in Kilo. On my compute node: in the file /var/log/libvirt/qemu/instance-000002c0.log
I can see in the /usr/bin/kvm command line that the first and second network interfaces' mac addresses are transposed from one boot to the next (lines wrapped for readability)

2015-11-05 20:13:39.125+0000: starting up
....
-netdev tap,fd=50,id=hostnet0,vhost=on,vhostfd=47 \
-device virtio-net-pci,netdev=hostnet0,id=net0,mac=fa:16:3e:df:3c:2a,bus=pci.0,addr=0x3 \
-netdev tap,fd=48,id=hostnet1,vhost=on,vhostfd=49 \
-device virtio-net-pci,netdev=hostnet1,id=net1,mac=fa:16:3e:b7:0d:88,bus=pci.0,addr=0x4 \
-netdev tap,fd=51,id=hostnet2,vhost=on,vhostfd=52 \
-device virtio-net-pci,netdev=hostnet2,id=net2,mac=fa:16:3e:5e:45:72,bus=pci.0,addr=0x5 \
-netdev tap,fd=53,id=hostnet3,vhost=on,vhostfd=54 \
-device virtio-net-pci,netdev=hostnet3,id=net3,mac=fa:16:3e:e9:68:03,bus=pci.0,addr=0x6 \
....
2015-11-06 22:36:52.829+0000: shutting down
2015-11-09 17:51:06.915+0000: starting up
....
-netdev tap,fd=26,id=hostnet0,vhost=on,vhostfd=42 \
-device virtio-net-pci,netdev=hostnet0,id=net0,mac=fa:16:3e:b7:0d:88,bus=pci.0,addr=0x3 \
-netdev tap,fd=43,id=hostnet1,vhost=on,vhostfd=44 \
-device virtio-net-pci,netdev=hostnet1,id=net1,mac=fa:16:3e:df:3c:2a,bus=pci.0,addr=0x4 \
-netdev tap,fd=47,id=hostnet2,vhost=on,vhostfd=48 \
-device virtio-net-pci,netdev=hostnet2,id=net2,mac=fa:16:3e:5e:45:72,bus=pci.0,addr=0x5 \
-netdev tap,fd=49,id=hostnet3,vhost=on,vhostfd=50 \
-device virtio-net-pci,netdev=hostnet3,id=net3,mac=fa:16:3e:e9:68:03,bus=pci.0,addr=0x6 \
...

The instance and it's ports were created via a heat template. The instance was not modified after first booting it. The instance was powered off and back on through the Horizon dashboard.