fix list_display

newsbox/admin.py

@@ -122,7 +122,7 @@ class NewsboxBaseAdmin(admin.ModelAdmin):
     save_as = True
 
     def get_list_display(self, request):
-        if not getattr(self.__class__, 'list_display', None):
+        if getattr(self.__class__, 'list_display', None) == admin.ModelAdmin.list_display:
             self.list_display = ['get_newsbox_title', 'newsbox_date_short', 'changestatus_link']
         return super(NewsboxBaseAdmin, self).get_list_display(request)
 
@@ -142,15 +142,19 @@ class NewsboxBaseAdmin(admin.ModelAdmin):
             icon_url = static('admin/img/icon-no.gif')
         url_name = '%s_%s_change_status' % (self.model._meta.model_name,
                                             self.model._meta.app_label)
-        return format_html('<a href="%s" title="%s"><img src="%s" alt="%s" /></a>',
+        return format_html(
+            '<a href="{}" title="{}"><img src="{}" alt="{}" /></a>',
             reverse('admin:%s' % url_name, args=[obj.pk, ]),
-            title, icon_url, obj.get_newsbox_status_display())
+            title,
+            icon_url,
+            obj.get_newsbox_status_display()
+        )
 
     changestatus_link.admin_order_field = 'newsbox_status'
     changestatus_link.short_description = _('published')
 
     def newsbox_date_short(self, obj):
-        return format_html('<span title="%s">%s</span>',
+        return format_html('<span title="{}">{}</span>',
             formats.date_format(obj.newsbox_publication_start_date, 'DATETIME_FORMAT'),
             formats.date_format(obj.newsbox_publication_start_date, 'SHORT_DATE_FORMAT')
         )