diff --git a/cas_server/models.py b/cas_server/models.py
index 0c44f6f..4626cce 100644
--- a/cas_server/models.py
+++ b/cas_server/models.py
@@ -18,7 +18,6 @@ from django.contrib import messages
 from django.utils.translation import ugettext_lazy as _
 from django.utils import timezone
 from django.utils.encoding import python_2_unicode_compatible
-from django.core.exceptions import ValidationError
 from django.core.mail import send_mail
 
 import re
diff --git a/cas_server/tests/test_models.py b/cas_server/tests/test_models.py
index 29a9dd4..bb338dd 100644
--- a/cas_server/tests/test_models.py
+++ b/cas_server/tests/test_models.py
@@ -81,6 +81,7 @@ class FederatedUserTestCase(TestCase, UserModels, FederatedIendityProviderModel)
         self.assertIsNone(user._attributs)
         self.assertIsNone(user.attributs)
 
+
 class FederateSLOTestCase(TestCase, UserModels):
     """test for the federated SLO model"""
     def test_clean_deleted_sessions(self):
@@ -275,7 +276,7 @@ class TicketTestCase(TestCase, UserModels, BaseServicePattern):
         self.assertIsNone(ticket.attributs)
 
 
-@mock.patch("cas_server.utils.last_version", lambda:"1.2.3")
+@mock.patch("cas_server.utils.last_version", lambda: "1.2.3")
 @override_settings(ADMINS=[("Ano Nymous", "ano.nymous@example.net")])
 @override_settings(CAS_NEW_VERSION_EMAIL_WARNING=True)
 class NewVersionWarningTestCase(TestCase):
diff --git a/cas_server/tests/test_view.py b/cas_server/tests/test_view.py
index 3d561a6..3ae6d17 100644
--- a/cas_server/tests/test_view.py
+++ b/cas_server/tests/test_view.py
@@ -49,7 +49,7 @@ class LoginTestCase(TestCase, BaseServicePattern, CanLogin):
         self.setup_service_patterns()
 
     @override_settings(CAS_NEW_VERSION_HTML_WARNING=True)
-    @mock.patch("cas_server.utils.last_version", lambda:"1.2.3")
+    @mock.patch("cas_server.utils.last_version", lambda: "1.2.3")
     @mock.patch("cas_server.utils.VERSION", "0.1.2")
     def test_new_version_available_ok(self):
         client = Client()
@@ -57,7 +57,7 @@ class LoginTestCase(TestCase, BaseServicePattern, CanLogin):
         self.assertIn(b"A new version of the application is available", response.content)
 
     @override_settings(CAS_NEW_VERSION_HTML_WARNING=True)
-    @mock.patch("cas_server.utils.last_version", lambda:None)
+    @mock.patch("cas_server.utils.last_version", lambda: None)
     @mock.patch("cas_server.utils.VERSION", "0.1.2")
     def test_new_version_available_badpypi(self):
         client = Client()
diff --git a/cas_server/tests/utils.py b/cas_server/tests/utils.py
index d020724..d8c781b 100644
--- a/cas_server/tests/utils.py
+++ b/cas_server/tests/utils.py
@@ -16,10 +16,6 @@ import django
 from django.test import Client
 from django.template import loader
 from django.utils import timezone
-if django.VERSION < (1, 8):
-    from django.template import Context
-else:
-    Context = lambda x:x
 
 import cgi
 import six
@@ -33,6 +29,13 @@ from cas_server import models
 from cas_server import utils
 
 
+if django.VERSION < (1, 8):
+    from django.template import Context
+else:
+    def Context(arg):
+        return arg
+
+
 def return_unicode(string, charset):
     """make `string` a unicode if `string` is a unicode or bytes encoded with `charset`"""
     if not isinstance(string, six.text_type):
diff --git a/cas_server/utils.py b/cas_server/utils.py
index d842e4a..4d1a554 100644
--- a/cas_server/utils.py
+++ b/cas_server/utils.py
@@ -654,8 +654,8 @@ def last_version():
     else:
         try:
             req = requests.get(settings.CAS_NEW_VERSION_JSON_URL)
-            data = json.loads(req.content)
-            versions = data["releases"].keys()
+            data = json.loads(req.text)
+            versions = list(data["releases"].keys())
             versions.sort()
             version = versions[-1]
             last_version._cache = (time.time(), version, True)
@@ -664,7 +664,7 @@ def last_version():
             KeyError,
             ValueError,
             requests.exceptions.RequestException
-        ) as error: # pragma: no cover (should not happen unless pypi is not available)
+        ) as error:  # pragma: no cover (should not happen unless pypi is not available)
             logger.error(
                 "Unable to fetch %s: %s" % (settings.CAS_NEW_VERSION_JSON_URL, error)
             )