netplan apply fails to rename network interfaces without reboot

Dear maintainers, hello.

After talking on netplan's IRC regarding a problem I had with netplan, I think it is possible that, with the member that supported me there, we found a bug.

First let me explain the context:
I am trying to create a script that sets up a bunch of identical machines, as part of this script I need to configure the network of the machines (I identify their mac address then try to attribute them names and network properties by generating a config and trying to apply it).
A big constraint for me is to get this setup script working without needing to reboot the machine.

*Report:*

Ubuntu Version: XUbuntu 20.04
Netplan Version: 0.100-0ubuntu4~20.04.3

I am creating a netplan configuration using match: macaddress: and set-name: to attribute new names to my network interfaces as shown here: https://pastebin.ubuntu.com/p/KHfhCNcPCB/
But when I run `sudo netplan apply` interfaces are not renamed.

Manually pulling them down with `sudo ip link set xxx down` before applying netplan configuration does not solve the situation.

Running `sudo netplan --debug apply` seems to have yielded something weird according to the person that helped me yesterday, and I quote:
> "DEBUG:Skipping non-physical interface: enp6s0" part of your log looks interesting... as enp6s0 actually IS a physical interface and should not be skipped."

Here is the sudo netplan --debug apply result: https://pastebin.ubuntu.com/p/mdK9MPR6P3/

Full disclosure: After reboot the interfaces have the correct name, however as stated at the beginning of this post, for my use-case I need to make it work without a reboot.

For reference, the IRC log where we found this behaviour is here (between 8:36 and 13:56): https://irclogs.ubuntu.com/2020/11/17/%23netplan.html