KeyError while trying to delegate to new role with CLI #1114

Description of issue:
I am trying to out the CLI examples, but could not get delegations to work with repo.py. Running exactly these commands:

Step (1)
$ repo.py --init

Step (2)
$ repo.py --key ed25519 --filename mykey
$ repo.py --delegate "README.*" --delegatee myrole --pubkeys tufkeystore/mykey.pub
$ repo.py --sign tufkeystore/mykey --role myrole

Current behavior:
Works without errors, up to the sign command, which throws:

Traceback (most recent call last):
  File "venv/bin/repo.py", line 1141, in <module>
    process_command_line_arguments(arguments)
  File "venv/bin/repo.py", line 260, in process_command_line_arguments
    sign_role(parsed_arguments)
  File "venv/bin/repo.py", line 587, in sign_role
    repository = repo_tool.load_repository(
  File "venv/lib/python3.8/site-packages/tuf/repository_tool.py", line 3133, in load_repository
    metadata_path = delegated_roles_filenames[rolename]
KeyError: 'myrole'

The new role is added to the target.json and also snapshot and timestamp updated, but there is no myrole.json created from the delegate command. This problem surfaces at the last command, it tries to load the repo again (for signing) and fails because it can not find metadata for the delegated role... After that all commands immediately fail at loading the repo.

Expected behavior:
That it creates a myrole.json and signs it with mykey.

Additional info:
I have also gone through the Advanced Tutorial and this works fine (creates the role metadata) running the functions from repository_tool.py directly.

Looking through the code I am not sure how it is intended to work with repo.py. Should the sign step create the missing role metadata instead? So signing before adding the delegation? But that does not work either:

$ repo.py --sign tufkeystore/mykey --role newrole
Error: Key: <ID HEX>