old_contents: try:
      import admin_notifications
      has_admin_notifications = True
  except ImportError:
      has_admin_notifications = False
  
  from models import Link
  
  # a global variable, showing whether linkcheck is still working
  still_updating = False
  
  def notification():
      if still_updating:
          return "Still checking. Please refresh this page in a short while. "
      else:
          broken_links = Link.objects.filter(ignore=False, url__status=False).count()
          if broken_links:
              return "You have %s broken link%s.<br>You can view or fix them using the <a href='/admin/linkcheck/'>Link Manager</a>." % (broken_links, broken_links>1 and "s" or "")
          else:
              return ''
  
  if has_admin_notifications:
      admin_notifications.register(notification)
  
new_contents: import admin_notifications
  
  from models import Link
  
  # a global variable, showing whether linkcheck is still working
  still_updating = False
  
  def notification():
      if still_updating:
          return "Still checking. Please refresh this page in a short while. "
      else:
          broken_links = Link.objects.filter(ignore=False, url__status=False).count()
          if broken_links:
              return "You have %s broken link%s.<br>You can view or fix them using the <a href='/admin/linkcheck/'>Link Manager</a>." % (broken_links, "s" if broken_links>1 else "")
          else:
              return ''
  
  admin_notifications.register(notification)
subject: Revert "Make admin_notifications really optional"