Comment 20 for bug 1569064

So based on Serge's observation that removing /etc/network/interfaces.d/* fixes this, and the log message

[CLOUDINIT] stages.py[INFO]: Applying network configuration from fallback: {'version': 1, 'config': [{'name': 'lxdbr0', 'mac_address': 'fe:68:41:8c:e7:dc', 'subnets': [{'type': 'dhcp'}], 'type': 'physical'}]}

I suspect that cloud-init is adding a /etc/network/interfaces.d/ configuration for lxdbr0, which it shouldn't do?