[Django]-Monkey patched django auth's login, now its tests fail

Couldn’t you simply wrap it in another view?

urls:

url(
    r'^accounts/login/$',
    'accounts.views.login',
    {"template_name":settings.LOGIN_TEMPLATE }
),

accounts.views:

from django.contrib.auth import views as auth_views   

def login(request, *args, **kwars):
    # do some stuff    
    response = auth_views.login(request, *args, **kwars)
    # more stuff
    return response

Like this, django.contrib.auth.tests will be testing the view which they were written for and you can write your own tests for the “more stuff” you need.