docs: def remote_interruptCommand(self, stepId, why):
          """Halt the current step."""
          log.msg("asked to interrupt current command: {0}".format(why))
          self.activity()
          if not self.command:
              # TODO: just log it, a race could result in their interrupting a
              # command that wasn't actually running
              log.msg(" .. but none was running")
              return
          self.command.doInterrupt()