Redmine

I am using the svn-head version of Redmine. When I try to migrate an existing Mantis setup (databases use LATIN2 encoding AFAIK), I can either:
- migrate with encoding[UTF-8] (I just leave the default) - this botches the user names and ticket texts quite a lot
- try to change the encoding used by rake - this breaks with

encoding [UTF-8]: LATIN2

rake aborted!
Validation failed: Lastname activerecord_error_invalid

Any ideas what encoding could work (I tried several, everything other than UTF-8 gives the same error)? And BTW, could the script just autodetect it, like phpmyadmin does?

The original database export is 40MB after compression, but if someone is willing to work on this I can trim it down and attach a smaller repro.