Invalid private key error when running fake-switches on centos8

[ansiblejunky]

Getting the following error with python 3.8 and pip install of fake-switches. Not sure what the problem might be.

[root@lab bin]# fake-switches
Traceback (most recent call last):
  File "/root/.pyenv/versions/3.8.2/bin/fake-switches", line 10, in <module>
    sys.exit(main())
  File "/root/.pyenv/versions/3.8.2/lib/python3.8/site-packages/fake_switches/cmd/main.py", line 39, in main
    ssh_service.hook_to_reactor(reactor)
  File "/root/.pyenv/versions/3.8.2/lib/python3.8/site-packages/fake_switches/transports/ssh_service.py", line 121, in hook_to_reactor
    b'ssh-rsa': keys.Key.fromString(data=host_private_key.encode())}
  File "/root/.pyenv/versions/3.8.2/lib/python3.8/site-packages/twisted/conch/ssh/keys.py", line 199, in fromString
    return method(data, passphrase)
  File "/root/.pyenv/versions/3.8.2/lib/python3.8/site-packages/twisted/conch/ssh/keys.py", line 442, in _fromString_PRIVATE_OPENSSH
    rsa.RSAPrivateNumbers(
  File "/root/.pyenv/versions/3.8.2/lib/python3.8/site-packages/cryptography/hazmat/primitives/asymmetric/rsa.py", line 367, in private_key
    return backend.load_rsa_private_numbers(self)
  File "/root/.pyenv/versions/3.8.2/lib/python3.8/site-packages/cryptography/hazmat/backends/openssl/backend.py", line 602, in load_rsa_private_numbers
    return _RSAPrivateKey(self, rsa_cdata, evp_pkey)
  File "/root/.pyenv/versions/3.8.2/lib/python3.8/site-packages/cryptography/hazmat/backends/openssl/rsa.py", line 389, in __init__
    raise ValueError("Invalid private key", errors)
ValueError: ('Invalid private key', [_OpenSSLErrorWithText(code=67764348, lib=4, func=160, reason=124, reason_text=b'error:040A007C:rsa routines:RSA_check_key_ex:dmp1 not congruent to d'), _OpenSSLErrorWithText(code=67764349, lib=4, func=160, reason=125, reason_text=b'error:040A007D:rsa routines:RSA_check_key_ex:dmq1 not congruent to d'), _OpenSSLErrorWithText(code=67764350, lib=4, func=160, reason=126, reason_text=b'error:040A007E:rsa routines:RSA_check_key_ex:iqmp not inverse of q')])

pip installs..

[root@lab bin]# pip list
Package        Version
-------------- -------
appdirs        1.4.4
cffi           1.14.5
constantly     15.1.0
cryptography   3.4.7
fake-switches  1.3.9
incremental    21.3.0
lxml           4.6.3
netaddr        0.8.0
pip            19.2.3
pyasn1         0.4.8
pycparser      2.20
setuptools     41.2.0
tftpy          0.8.0
Twisted        16.6.0
zope.interface 5.4.0

[ansiblejunky]

It appears the problem was the cryptography version. I downgraded to version 3.0 and it works now.
pip install cryptography==3.0