Jruby 1.6.0 and invalid foreign key on destroy

I’m using jruby 1.6.0 and postgres.
With 1.5.x versions I have no problems on destroying records.
Now with 1.6.0 when I do a destroy I have this strange message:

uninitialized constant ArJdbc::PostgreSQL::InvalidForeignKey

I’ve tried to delete my foreign keys but the error persists.
What’s the problem?