Exception with custom Retry class to set BACKOFF_MAX

I've built a helper function and custom Retry class so I can set BACKOFF_MAX for a requests session as per this solution:

from requests import Session
from requests.adapters import HTTPAdapter, Retry


class RetryRequest(Retry):

    def __init__(self, backoff_max: int, **kwargs):
        super().__init__(**kwargs)
        self.BACKOFF_MAX = backoff_max


def create_session(
    retries: int,
    backoff_factor: float,
    backoff_max: int,
    user_agent: str = "*",
    referer: str = None,
) -> Session:
    session = Session()
    retries_spec = RetryRequest(
        total=retries,
        backoff_factor=backoff_factor,
        backoff_max=backoff_max,
    )
    session.mount("https://", HTTPAdapter(max_retries=retries_spec))
    headers = {"User-Agent": user_agent, "Referer": referer}
    session.headers.update(headers)
    return session

The session has been working fine for weeks but today it raised the following exception after it had been online for a few hours:

  File "/Users/username/GitHub/polgara/apis/base_endpoint.py", line 54, in _get
    response = self.client.session.get(url=url, headers=headers, params=params)
  File "/Users/username/miniconda3/envs/capra_production/lib/python3.10/site-packages/requests/sessions.py", line 600, in get
    return self.request("GET", url, **kwargs)
  File "/Users/username/miniconda3/envs/capra_production/lib/python3.10/site-packages/requests/sessions.py", line 587, in request
    resp = self.send(prep, **send_kwargs)
  File "/Users/username/miniconda3/envs/capra_production/lib/python3.10/site-packages/requests/sessions.py", line 701, in send
    r = adapter.send(request, **kwargs)
  File "/Users/username/miniconda3/envs/capra_production/lib/python3.10/site-packages/requests/adapters.py", line 489, in send
    resp = conn.urlopen(
  File "/Users/username/miniconda3/envs/capra_production/lib/python3.10/site-packages/urllib3/connectionpool.py", line 787, in urlopen
    retries = retries.increment(
  File "/Users/username/miniconda3/envs/capra_production/lib/python3.10/site-packages/urllib3/util/retry.py", line 581, in increment
    new_retry = self.new(
  File "/Users/username/miniconda3/envs/capra_production/lib/python3.10/site-packages/urllib3/util/retry.py", line 338, in new
    return type(self)(**params)
TypeError: RetryRequest.__init__() missing 1 required positional argument: 'backoff_max'

It looks like something has gone awry in requests and it has tried to create a new session with the RetryRequest class but because it usually only deals with a Retry class it didn't pass the custom parameter of backoff_max.

I could get around this by setting a default argument for backoff_max but this defeats the object of being able to customise it when I create the session to begin with.

Would anyone have any idea on how I'd be able to solve this?

requests version is 2.28.2

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