Unable to add rack controller

When installing a fresh 2.8 deployment with separate region and rack controllers adding the rack controller fails. Steps to reproduce:

1. Setup region controller following https://maas.io/docs/install-from-a-snap

sudo snap install maas --channel=2.8/stable
sudo snap install maas-test-db --channel=2.8/stable
sudo maas init region --database-uri maas-test-db:///
sudo maas createadmin

2. Add rack
sudo maas init rack
MAAS URL [default=http://10.29.157.66:5240/MAAS]: http://10.29.157.93:5240/MAAS
Secret:
Secret: 917fce44021b67e405e71f48d456af30
Traceback (most recent call last):
  File "/snap/maas/7328/bin/maas", line 33, in <module>
    sys.exit(load_entry_point('maas==2.8.0', 'console_scripts', 'maas')())
  File "/snap/maas/7328/lib/python3.6/site-packages/maascli/__init__.py", line 45, in main
    options.execute(options)
  File "/snap/maas/7328/lib/python3.6/site-packages/maascli/snappy.py", line 661, in __call__
    raise exc
  File "/snap/maas/7328/lib/python3.6/site-packages/maascli/snappy.py", line 658, in __call__
    self.handle(options)
  File "/snap/maas/7328/lib/python3.6/site-packages/maascli/snappy.py", line 1005, in handle
    set_rpc_secret(rpc_secret)
  File "/snap/maas/7328/lib/python3.6/site-packages/maascli/snappy.py", line 318, in set_rpc_secret
    with open(secret_path, "w") as fp:
FileNotFoundError: [Errno 2] No such file or directory: '/var/snap/maas/7328/var/lib/maas/secret'