1: load original target
2: check for deps
3: load deps that you do not have
4: goto 2 if needed
5: normal portage operation

store locally:
	for full portage:
		$PF last-date-of-update

	for installed ebuilds:
		installed ebuilds (version at install time)
		distfiles
		optionally:
			installed ebuilds (newest revision of the ebuild for same version)
			installed ebuilds (newest revision of best version)