Intermittent 'Failed to match request state with session state' with Django adaptor

This issue is for a: (mark with an x)

- [x] bug report -> please search issues before submitting
- [ ] feature request
- [ ] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)

Minimal steps to reproduce

Default Django setup as per Azure-Samples/ms-identity-python-django-tutorial

Any log messages given by the failure

Django error email report snippet:

•	/opt/master/venv/lib/python3.8/site-packages/ms_identity_web/__init__.py in _verify_state 
259.	
260.	            raise AuthSecurityError("Failed to match request state with session state")
261.	
Local Vars
Variable	Value
req_params	{'code': '0.AQ<redacted>AA',
 'session_state': 'aa8b2958-b1c4-4e71-a95c-a682c2180777',
 'state': 'c5af71b0-fc95-4d3c-896e-a5c8306d86f7'}
self	<ms_identity_web.IdentityWebPython object at 0x7fbda61c59a0>
session_state	None
state	'c5af71b0-fc95-4d3c-896e-a5c8306d86f7'

Expected/desired behavior

session_state should not be None and should match state param at https://github.com/Azure-Samples/ms-identity-python-samples-common/blob/main/ms_identity_web/__init__.py#L258

OS and Version?

Django 2.2 using gunicorn on Ubuntu 20.04 EC2

Versions

MSAL 1.12.0

Mention any other details that might be useful

Seems easier to repro using Firefox, but have seen using Edge/Chrome.

從 ms_identity_web/init.py 開始，特別檢查回報行附近的 _verify_state，並比較在使用 gunicorn 的 Django 2.2 設定中工作階段狀態的儲存與讀取方式。使用連結的 Django 教學課程重現這個間歇性故障，並注意 Firefox、Edge 和 Chrome。完成的標準是 callback 不再將 session_state 視為 None，且相關測試或重現確認狀態值相符。