JRuby on Rails db:test:purge fails! Need help

My system is:
Ubuntu 10.04, JRuby 1.6.7, Ruby on Rails 3.0.9,
activerecord-jdbc-adapter 1.2.2, activerecord-jdbcderby-adapter

Up until a few days ago, "rake test:units" was working fine, but now
suddenly it fails with the following message: