Archive:+copy-packages creates job which oopses when async-copying from private to public archive

https://oops.canonical.com/?oopsid=OOPS-17916a2f6396f0957b5eb5cf1833f2fb

  CannotCopy: simplecv 1.2-1ubuntu3 in precise (Cannot copy restricted files to a public archive without explicit unembargo option.)

    Traceback (most recent call last):
  Module lazr.jobrunner.jobrunner, line 194, in runJobHandleError
    self.runJob(job, fallback)
  Module lp.services.job.runner, line 295, in runJob
    super(BaseJobRunner, self).runJob(IRunnableJob(job), fallback)
  Module lazr.jobrunner.jobrunner, line 162, in runJob
    job.run()
  Module lp.soyuz.model.packagecopyjob, line 505, in run
    self.attemptCopy()
  Module lp.soyuz.model.packagecopyjob, line 584, in attemptCopy
    unembargo=self.unembargo)
  Module lp.soyuz.scripts.packagecopier, line 669, in do_copy
    raise CannotCopy(error_text)
CannotCopy: simplecv 1.2-1ubuntu3 in precise (Cannot copy restricted files to a public archive without explicit unembargo option.)