Postgres adapter error after gems:unpack

I have installed following gems:

actionmailer (2.3.8)
actionpack (2.3.8)
activerecord (2.3.8)
activeresource (2.3.8)
activesupp开发者_JAVA百科ort (2.3.8)
open4 (1.0.1)
pg (0.9.0)
rack (1.1.0)
rails (2.3.8)
rake (0.8.7)

My application uses postgres as db and pg gem and it had been working fine by the time I done

rake rails:freeze:gems
rake gems:unpack

It copied rails and pg gem to /vendor but after that I have following error when I try to run server:

Please install the postgresql adapter: `gem install activerecord-postgresql-adapter` (no such file to load -- pg_ext) (RuntimeError)

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Ok, the solution is:

rake gems:build

The whole thing is described here: http://reborg.tumblr.com/post/99668398/rails-gems-unpack-native