When updating from VyOS 1.2.5 to 1.3 latest rolling (1.3-rolling-202006210117), interface configuration `peth` disappeared.
Reproducing steps:
```
set interfaces pseudo-ethernet peth1 address '172.16.0.1/24'
set interfaces pseudo-ethernet peth1 link 'eth1'
set interfaces pseudo-ethernet peth1 mode 'private'
commit
```
And just update to the latest rolling
```
add system images https://downloads.vyos.io/rolling/current/amd64/vyos-rolling-latest.iso
```
After reboot pethX will be deleted from config
```
vyos@vyos:~$ cat /tmp/boot-config-trace
Traceback (most recent call last):
File "/usr/libexec/vyos/vyos-boot-config-loader.py", line 143, in <module>
commit_out = session.commit()
File "/usr/lib/python3/dist-packages/vyos/configsession.py", line 156, in commit
out = self.__run_command([COMMIT])
File "/usr/lib/python3/dist-packages/vyos/configsession.py", line 128, in __run_command
raise ConfigSessionError(output)
vyos.configsession.ConfigSessionError: [ interfaces pseudo-ethernet peth1 ]
Link device must be set for pseudo-ethernet "peth1"
[[interfaces pseudo-ethernet peth1]] failed
Commit failed
```