I wrote this ticket yesterday. I'm converting a large app with lots of migrations to 2.1 and rake db:test:prepare fails. It's trying to play sql statements chunk by chunk from db/development_structure.sql into the test database, but when it gets to the insert statements at the end which represent the contents of schema_migrations, it fails with an invalid SQL error.
I'm not sure whether this is because the chunk of sql is just too long, or that connection.execute wants only a single sql statement, but the patch in the ticket fixes the generation of the file to put empty lines between each insert, which causes the rake task to execute them one by one, and alleviates the problem.
Might be important?!
More on this at http://talklikeaduck.denhaven2.com/articles/2008/05/15/rails-2-1rc1-and-the-enhanced-migrations-plugin