Sys-subsystem-net-devices-eth0.device timed out

I added a route to the configuration of some EC2 instance like:

networking.interfaces.eth0.ipv4.routes = [ ... ];

After deploying this I noticed the route wasn’t configured and the following appeared in my journal:

systemd[1]: sys-subsystem-net-devices-eth0.device: Job sys-subsystem-net-devices-eth0.device/start timed out.
systemd[1]: Timed out waiting for device sys-subsystem-net-devices-eth0.device.
systemd[1]: Dependency failed for Address configuration of eth0.
systemd[1]: network-addresses-eth0.service: Job network-addresses-eth0.service/start failed with result 'dependency'.

Why is sys-subsystem-net-devices-eth0.device timing out?

I do see the following in my journal soon after booting which might have something to do with it:

systemd-udevd[653]: Error changing net interface name 'eth0' to 'ens5': Device or resource busy
systemd-udevd[653]: could not rename interface '2' from 'eth0' to 'ens5': Device or resource busy

Note that this is a fairly minimal NixOS 19.03 configuration running on EC2.