Added 'groups' to UserAdmin.filter_horizontal

Is there some reason it's not there already?

Our list of groups is very cumbersome to use with the standard widget.

django/contrib/auth/admin.py

@@ -56,7 +56,7 @@ class UserAdmin(admin.ModelAdmin):
     list_filter = ('is_staff', 'is_superuser', 'is_active', 'groups')
     search_fields = ('username', 'first_name', 'last_name', 'email')
     ordering = ('username',)
-    filter_horizontal = ('user_permissions',)
+    filter_horizontal = ('groups', 'user_permissions',)
 
     def get_fieldsets(self, request, obj=None):
         if not obj: