http_headers - Server requested a client certificate issued by one of the following CAs

[wondex]

Describe the bug

Traceback (most recent call last):
  File "/opt/rh/rh-python38/root/usr/local/lib/python3.8/site-packages/sslyze/scanner.py", line 264, in get_results
    result = implementation_cls.result_for_completed_scan_jobs(
  File "/opt/rh/rh-python38/root/usr/local/lib/python3.8/site-packages/sslyze/plugins/http_headers_plugin.py", line 188, in result_for_completed_scan_jobs
    return completed_scan_jobs[0].result()
  File "/opt/rh/rh-python38/root/usr/lib64/python3.8/concurrent/futures/_base.py", line 432, in result
    return self.__get_result()
  File "/opt/rh/rh-python38/root/usr/lib64/python3.8/concurrent/futures/_base.py", line 388, in __get_result
    raise self._exception
  File "/opt/rh/rh-python38/root/usr/lib64/python3.8/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/opt/rh/rh-python38/root/usr/local/lib/python3.8/site-packages/sslyze/plugins/http_headers_plugin.py", line 204, in _retrieve_and_analyze_http_response
    ssl_connection.connect()
  File "/opt/rh/rh-python38/root/usr/local/lib/python3.8/site-packages/sslyze/connection_helpers/tls_connection.py", line 293, in connect
    self.ssl_client.do_handshake()
  File "/opt/rh/rh-python38/root/usr/local/lib64/python3.8/site-packages/nassl/ssl_client.py", line 201, in do_handshake
    raise ClientCertificateRequested(self.get_client_CA_list())
nassl.ssl_client.ClientCertificateRequested: Server requested a client certificate issued by one of the following CAs: /CN=<CN1>, /CN=<CN2>, /CN=<CN3>.

To Reproduce
Install SSLyze using: pip
Run the following command: /opt/rh/rh-python38/root/usr/bin/python3.8 -m sslyze --regular

Expected behavior
Successful scan

Python environment (please complete the following information):
OS: Red Hat Enterprise Linux Server release 7.9 (Maipo)
Python version: 3.8
SSLyzeL: 4.0.4

Additional context
command:
openssl s_client -connect host:port

output:
CONNECTED(00000003)
depth=0 CN =
verify error:num=18:self signed certificate
verify return:1
depth=0 CN =
verify return:1
140045356537744:error:14094412:SSL routines:ssl3_read_bytes:sslv3 alert bad certificate:s3_pkt.c:1493:SSL alert number 42
140045356537744:error:140790E5:SSL routines:ssl23_write:ssl handshake failure:s23_lib.c:177:

[nabla-c0d3]

This is expected behavior - SSLyze correctly returns the ClientCertificateRequested error. A client certificate is needed to complete the scan.