diff --git a/django/contrib/admin/sites.py b/django/contrib/admin/sites.py
index e0f43dfbf..bbb97abed 100644
--- a/django/contrib/admin/sites.py
+++ b/django/contrib/admin/sites.py
@@ -223,12 +223,12 @@ class AdminSite(object):
             url(r'^logout/$',
                 wrap(self.logout),
                 name='logout'),
-            url(r'^password_change/$',
-                wrap(self.password_change, cacheable=True),
-                name='password_change'),
-            url(r'^password_change/done/$',
-                wrap(self.password_change_done, cacheable=True),
-                name='password_change_done'),
+            #url(r'^password_change/$',
+            #    wrap(self.password_change, cacheable=True),
+            #    name='password_change'),
+            #url(r'^password_change/done/$',
+            #    wrap(self.password_change_done, cacheable=True),
+            #    name='password_change_done'),
             url(r'^jsi18n/$',
                 wrap(self.i18n_javascript, cacheable=True),
                 name='jsi18n'),
@@ -313,6 +313,9 @@ class AdminSite(object):
         """
         Displays the login form for the given HttpRequest.
         """
+        url = "/accounts/login/?next="+request.get_full_path()
+        return http.HttpResponseRedirect(url)
+        
         from django.contrib.auth.views import login
         context = {
             'title': _('Log in'),
diff --git a/django/contrib/admin/templates/admin/base.html b/django/contrib/admin/templates/admin/base.html
index 63d4419fa..f35121bf2 100644
--- a/django/contrib/admin/templates/admin/base.html
+++ b/django/contrib/admin/templates/admin/base.html
@@ -32,9 +32,11 @@
                 {% if docsroot %}
                     <a href="{{ docsroot }}">{% trans 'Documentation' %}</a> /
                 {% endif %}
+                {% comment %}
                 {% if user.has_usable_password %}
                 <a href="{% url 'admin:password_change' %}">{% trans 'Change password' %}</a> /
                 {% endif %}
+                {% endcomment %}
                 <a href="{% url 'admin:logout' %}">{% trans 'Log out' %}</a>
             {% endblock %}
         </div>
diff --git a/django/contrib/auth/forms.py b/django/contrib/auth/forms.py
index 081d9e558..d5e869311 100644
--- a/django/contrib/auth/forms.py
+++ b/django/contrib/auth/forms.py
@@ -73,9 +73,9 @@ class UserCreationForm(forms.ModelForm):
         'duplicate_username': _("A user with that username already exists."),
         'password_mismatch': _("The two password fields didn't match."),
     }
-    username = forms.RegexField(label=_("Username"), max_length=30,
+    username = forms.RegexField(label=_("Username"), max_length=64,
         regex=r'^[\w.@+-]+$',
-        help_text=_("Required. 30 characters or fewer. Letters, digits and "
+        help_text=_("Required. 64 characters or fewer. Letters, digits and "
                       "@/./+/-/_ only."),
         error_messages={
             'invalid': _("This value may contain only letters, numbers and "
@@ -123,8 +123,8 @@ class UserCreationForm(forms.ModelForm):
 
 class UserChangeForm(forms.ModelForm):
     username = forms.RegexField(
-        label=_("Username"), max_length=30, regex=r"^[\w.@+-]+$",
-        help_text=_("Required. 30 characters or fewer. Letters, digits and "
+        label=_("Username"), max_length=64, regex=r"^[\w.@+-]+$",
+        help_text=_("Required. 64 characters or fewer. Letters, digits and "
                       "@/./+/-/_ only."),
         error_messages={
             'invalid': _("This value may contain only letters, numbers and "
diff --git a/django/contrib/auth/models.py b/django/contrib/auth/models.py
index 51537530e..b7b7b036f 100644
--- a/django/contrib/auth/models.py
+++ b/django/contrib/auth/models.py
@@ -365,8 +365,8 @@ class AbstractUser(AbstractBaseUser, PermissionsMixin):
 
     Username, password and email are required. Other fields are optional.
     """
-    username = models.CharField(_('username'), max_length=30, unique=True,
-        help_text=_('Required. 30 characters or fewer. Letters, numbers and '
+    username = models.CharField(_('username'), max_length=64, unique=True,
+        help_text=_('Required. 64 characters or fewer. Letters, numbers and '
                     '@/./+/-/_ characters'),
         validators=[
             validators.RegexValidator(re.compile('^[\w.@+-]+$'), _('Enter a valid username.'), 'invalid')
diff --git a/django/core/serializers/json.py b/django/core/serializers/json.py
index 64357bf9d..1cdd6f3b6 100644
--- a/django/core/serializers/json.py
+++ b/django/core/serializers/json.py
@@ -100,6 +100,8 @@ class DjangoJSONEncoder(json.JSONEncoder):
             return r
         elif isinstance(o, decimal.Decimal):
             return str(o)
+        elif isinstance(o, datetime.timedelta):
+            return o.days * 24*60*60 + o.seconds
         else:
             return super(DjangoJSONEncoder, self).default(o)
 
diff --git a/django/db/models/query.py b/django/db/models/query.py
index 1075407ae..4bc2df5c8 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -302,9 +302,8 @@ class QuerySet(object):
         if num == 1:
             return clone._result_cache[0]
         if not num:
-            raise self.model.DoesNotExist(
-                "%s matching query does not exist." %
-                self.model._meta.object_name)
+            raise self.model.DoesNotExist(u"%s matching query does not exist. Lookup parameters were %s"
+                    % (self.model._meta.object_name, kwargs))
         raise self.model.MultipleObjectsReturned(
             "get() returned more than one %s -- it returned %s!" %
             (self.model._meta.object_name, num))