port avoid-regen-cert to trusty.
merge up
apply same importerror check to trusty, keeping precise and trusty in sync.
  David Britton 2014-06-28 apply same importerror check to trusty, keeping precise and trusty in sync.
  David Britton 2014-06-28 [merge] merge up
  David Britton 2014-06-20 port avoid-regen-cert to trusty.