Fixed #19327 -- Added handling of double login attempts in admin.

Thanks to Krzysztof Jurewicz for initial patch and
adupin for tests.

1 files changed, 3 insertions, 1 deletions

diff --git a/django/contrib/admin/sites.py b/django/contrib/admin/sites.py
index 07d1ec7804..8345543707 100644
--- a/django/contrib/admin/sites.py
+++ b/django/contrib/admin/sites.py
@@ -2,7 +2,7 @@ from functools import update_wrapper
 from django.http import Http404, HttpResponseRedirect
 from django.contrib.admin import ModelAdmin, actions
 from django.contrib.admin.forms import AdminAuthenticationForm
-from django.contrib.auth import REDIRECT_FIELD_NAME
+from django.contrib.auth import logout as auth_logout, REDIRECT_FIELD_NAME
 from django.contrib.contenttypes import views as contenttype_views
 from django.views.decorators.csrf import csrf_protect
 from django.db.models.base import ModelBase
@@ -193,6 +193,8 @@ class AdminSite(object):
         cacheable=True.
         """
         def inner(request, *args, **kwargs):
+            if LOGIN_FORM_KEY in request.POST and request.user.is_authenticated():
+                auth_logout(request)
             if not self.has_permission(request):
                 if request.path == reverse('admin:logout',
                                            current_app=self.name):