Maybe it's bad media, doesn't look it at first glance though.
I burnt the DVD - Prime x86_64.
Booted.
Selected "Install or Upgrade".
Chose Local CDROM.
Had the media pop out and an error - Terminal said "unable to mount loop
back".
Tried HTTP install pointed at the development tree but it complained
about "repo doesn't match the media".
Anybody else, known issue?