Comment 3 for bug 1853047

Here is the code:

https://git.launchpad.net/cpe-foundation/tree/foundationcloudengine/foundationcloudengine/maas_config_networks.py

Here is the networks.yaml it uses:
https://git.launchpad.net/cpe-deployments/tree/config/networks.yaml?h=solutionsqa/fcb/project/stable-stein-bionic-production

This code has been stable for a long time; this is a race condition. If I had to guess, maas is doing something like discovering the vlan on the destination fabric between when we read what vlans are on what fabrics and when we try to put vlans on the correct fabrics.