Comment 2 for bug 138714

I was upgrading from current version of feisty (I update regularly) to gutsy via changing entries in /etc/apt/sources.list
and then 'apt-get update' followed by 'apt-get dist-upgrade'

MySql failed with a message re a bad hosts table.
I believe the 4.x to 5.x change in mysql modified several table layouts.

On the internet some recommendations were to just 'rm blat' a number of offending tables and let mysql rebuild them.
That partially worked, but also dropped the magical debian-maint@localhost (or something similar)
user record. I then followed internet recommendations for fixing that, but that failed as well. I was left
with something that complained about missing entries in some key tables when running
      mysqlcheck -A --auto-repair
I finally just apt-get remove'ed with purge, then reinstalled. It now works.