Rails 3.1 RC4 has broken migrations

Rails 3.1 RC4 has broken migrations

$ jruby -v
jruby 1.6.2 (ruby-1.8.7-p330) (2011-05-23 e2ea975) (Java HotSpot(TM)
64-Bit Server VM 1.6.0_24) [darwin-x86_64-java]

$ jruby -S rails -v
Rails 3.1.0.rc4

$ jruby -S rails new myapp -d jdbcpostgresql
[...]
$jruby -S rake db:create
[...]
$ jruby -S rails g model user name:string
      invoke active_record
      create db/migrate/20110609233144_create_users.rb
      create app/models/user.rb
      invoke test_unit
      create test/unit/user_test.rb
      create test/fixtures/users.yml

jruby -S rake db:migrate

$ jruby -S rake db:migrate --trace
** Invoke db:migrate (first_time)
** Invoke environment (first_time)
** Execute environment
** Invoke db:load_config (first_time)
** Invoke rails_env (first_time)
** Execute rails_env
** Execute db:load_config
** Execute db:migrate
== CreateUsers: migrating

jruby -S rake db:migrate --trace executed for Rails 3.0.8 does not
display any errors. So I guess this might be something broken in Rails
3.1 RC4 internals.