Three/Sony wifi tethering fox for android 5

The fix for tethering on Z1 sony xperia after android 5 update:

Fault: on turning on tethering, the wifi network comes up, but the error "an error occured during tethering" appears.
You can connect to the network but there is no routing from wifi to OTA (3/4G interface).

Fix:
Take a machine connected to the internet, for example, windows 7 laptop.
Plug Z1 in via USB lead.
Turn on tethering.
Turn on USB tethering.
Windows will install an rndis device.

Once this is done, you can disconnect the machine from it's internet connection.

Try the machine, it should now have internet access via the USB connection.
If this works, disconnect the cable, and turn the wifi on for the tethering on the phone. If already on, connect to it.
Now should be connected via wifi tethering.

It seems the tethering code needs to connect once to overwrite some of the config with the details for android 5.