CLI failure: 'repo.py --sign' fails for RSA #998

rm -rf tuf-test ; mkdir tuf-test ; cd tuf-test
repo.py --init --bare
repo.py --key rsa --filename root_key --pw 1234
repo.py --trust --pubkeys tufkeystore/root_key.pub --role root
repo.py --sign tufkeystore/root_key --role root --no_release
cd .. ; rm -r tuf-test

Traceback (most recent call last):
  File "/path/to/securesystemslib/securesystemslib/pyca_crypto_keys.py", line 990, in _decrypt
    file_contents.split(_ENCRYPTION_DELIMITER)
ValueError: not enough values to unpack (expected 5, got 1)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/path/to/tuf/scripts/repo.py", line 450, in import_privatekey_from_file
    password)
  File "/path/to/securesystemslib/securesystemslib/keys.py", line 1418, in decrypt_key
    securesystemslib.pyca_crypto_keys.decrypt_key(encrypted_key, passphrase)
  File "/path/to/securesystemslib/securesystemslib/pyca_crypto_keys.py", line 847, in decrypt_key
    json_data = _decrypt(encrypted_key, password)
  File "/path/to/securesystemslib/securesystemslib/pyca_crypto_keys.py", line 993, in _decrypt
    raise securesystemslib.exceptions.CryptoError('Invalid encrypted file.')
securesystemslib.exceptions.CryptoError: Invalid encrypted file.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/silvano/.local/bin/repo.py", line 7, in <module>
    exec(compile(f.read(), __file__, 'exec'))
  File "/path/to/tuf/scripts/repo.py", line 1139, in <module>
    process_command_line_arguments(arguments)
  File "/path/to/tuf/scripts/repo.py", line 260, in process_command_line_arguments
    sign_role(parsed_arguments)
  File "/path/to/tuf/scripts/repo.py", line 592, in sign_role
    role_privatekey = import_privatekey_from_file(keypath, parsed_arguments.pw)
  File "/path/to/tuf/scripts/repo.py", line 457, in import_privatekey_from_file
    encrypted_key, 'rsassa-pss-sha256', password)
  File "/path/to/securesystemslib/securesystemslib/keys.py", line 963, in import_rsakey_from_private_pem
    securesystemslib.formats.PEMRSA_SCHEMA.check_match(pem)
  File "/path/to/securesystemslib/securesystemslib/schema.py", line 205, in check_match
    ' but got ' + repr(object))
securesystemslib.exceptions.FormatError: Expected a string but got b'-----BEGIN RSA PRIVATE KEY-----\nProc-Type: 4,ENCRYPTED\nDEK-Info: AES-256-CBC,66390E8C0987C902E41A0A348B3D46A6\n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\n-----END RSA PRIVATE KEY-----\n'