There was code that was supposed to "catch upgrades from previous versions where
the root password wasn't set". But it is wrong in many regards:
- it is supposed to be executed against running server, but at this point server
  should be down, which makes this code no-op
- if the above is fixed, root password will be requested twice (initial root
  password request + this one)
- it asks for a password only once, while "initial root password request" asks
  twice (password + password verification)
- it may give false positive if unix socket based authentication is in effect

Removed this code since it didn't work for quite a while (at least since
mysql-5.1) and nobody cared about it.