Comment 2 for bug 1668347

Upstream pull request:
https://github.com/systemd/systemd/pull/5545

Sample packages with patch applied for zesty:
https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/2541

How to use:
Similar to bridge port cost, one can set [Bridge] Priority= setting in the .network file for a given ether device, e.g.:

/etc/systemd/network/10-ens3.network
[Match]
Name=ens3

[Bridge]
Priority=33