barbicanclient does not catch exceptions thrown by "secrets.payload" API

As per the barbican client documentation, the get secrets APIs will throw below wrapper exceptions for HTTP Errors:

    barbicanclient.exceptions.HTTPAuthError – 401 Responses
    barbicanclient.exceptions.HTTPClientError – 4xx Responses
    barbicanclient.exceptions.HTTPServerError – 5xx Responses

But in the below code snippet, the HTTP errors from "secrets.payload" API are not catched and wrapped with barbicanclient exceptions.
 .
 .
secrets = barbican_client.secrets.get(secrete_reference, u'text/plain')
secret_payload = secrets.payload
 .
 .

Exception Trace for HTTP 500 :
======================================================
  File "/root/cfs_exec_dash/get_secrets_test.py", line 39, in get_secret
    secrets.payload
  File "/usr/lib/python2.7/site-packages/python_barbicanclient-3.3.0-py2.7.egg/barbicanclient/secrets.py", line 188, in payload
    self._fetch_payload()
  File "/usr/lib/python2.7/site-packages/python_barbicanclient-3.3.0-py2.7.egg/barbicanclient/secrets.py", line 259, in _fetch_payload
    payload = self._api._get_raw(payload_url, headers=headers)
  File "/usr/lib/python2.7/site-packages/python_barbicanclient-3.3.0-py2.7.egg/barbicanclient/client.py", line 85, in _get_raw
    return self.request(path, 'GET', *args, **kwargs).content
  File "/usr/lib/python2.7/site-packages/python_barbicanclient-3.3.0-py2.7.egg/barbicanclient/client.py", line 64, in request
    resp = super(_HTTPClient, self).request(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/python_keystoneclient-2.1.1-py2.7.egg/keystoneclient/adapter.py", line 95, in request
    return self.session.request(url, method, **kwargs)
  File "/usr/lib/python2.7/site-packages/python_keystoneclient-2.1.1-py2.7.egg/keystoneclient/utils.py", line 337, in inner
    return func(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/python_keystoneclient-2.1.1-py2.7.egg/keystoneclient/session.py", line 305, in request
    auth_headers = self.get_auth_headers(auth)
  File "/usr/lib/python2.7/site-packages/python_keystoneclient-2.1.1-py2.7.egg/keystoneclient/session.py", line 622, in get_auth_headers
    return auth.get_headers(self, **kwargs)
  File "/usr/lib/python2.7/site-packages/python_keystoneclient-2.1.1-py2.7.egg/keystoneclient/auth/base.py", line 143, in get_headers
    token = self.get_token(session)
  File "/usr/lib/python2.7/site-packages/python_keystoneclient-2.1.1-py2.7.egg/keystoneclient/auth/identity/base.py", line 203, in get_token
    return self.get_access(session).auth_token
  File "/usr/lib/python2.7/site-packages/python_keystoneclient-2.1.1-py2.7.egg/keystoneclient/auth/identity/base.py", line 249, in get_access
    self.auth_ref = self.get_auth_ref(session)
  File "/usr/lib/python2.7/site-packages/python_keystoneclient-2.1.1-py2.7.egg/keystoneclient/auth/identity/v3/base.py", line 190, in get_auth_ref
    authenticated=False, log=False, **rkwargs)
  File "/usr/lib/python2.7/site-packages/python_keystoneclient-2.1.1-py2.7.egg/keystoneclient/session.py", line 506, in post
    return self.request(url, 'POST', **kwargs)
  File "/usr/lib/python2.7/site-packages/python_keystoneclient-2.1.1-py2.7.egg/keystoneclient/utils.py", line 337, in inner
    return func(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/python_keystoneclient-2.1.1-py2.7.egg/keystoneclient/session.py", line 406, in request
    raise exceptions.from_response(resp, method, url)
InternalServerError: An unexpected error prevented the server from fulfilling your request. (HTTP 500) (Request-ID: req-8d1d5e0c-2682-4969-af6f-78df4e35b37d)