After investigations, commit the proposed patch by kklimonda presented with the following introduction : cm/templates/site/login_form.html template uses a relative url for the form action, which seems to break deployment in the subfolder when trailing slash is missing (the form redirects to the upper folder breaking login). Using {% url login %} (as in the attached patch) instead would fix the issue.

from django.test import TestCase
from django.test.client import Client
from django.core import management

from cm.models import *

class HistoryTest(TestCase):
    fixtures = ['test_comments',]
    
    def test_revert(self):
        text = Text.objects.all()[0]
        text_version = text.last_text_version
        text.revert_to_version(text_version.key)