docs: def mugshot2to3(old):
      """
      Upgrader for L{Mugshot} from version 2 to version 3, which re-thumbnails
      the mugshot to take into account the new value of L{Mugshot.smallerSize}.
      """
      new = old.upgradeVersion(Mugshot.typeName, 2, 3,
                               person=old.person,
                               type=old.type,
                               body=old.body,
                               smallerBody=old.smallerBody)
      new.smallerBody = new.makeThumbnail(
          new.body.open(), new.person, new.type[len('image/'):], smaller=True)
      return new