postgres: não é possível instalar o postgresql-contrib-9.1

Question

A versão do meu sistema é Ubuntu 13.10 64bit.

Encontrei esse problema configurando o PostgreSQL em um aplicativo Rails.

Primeiro, corri rake db:migrate e mostrei um erro:

-- enable_extension("hstore")
rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:

PG::UndefinedFile: ERROR:  could not open extension control file "/usr/share/postgresql/9.1/extension/hstore.control": No such file or directory
: CREATE EXTENSION IF NOT EXISTS "hstore"/home/user/.rvm/gems/ruby-2.1.1/gems/rack-mini-profiler-0.9.1/lib/patches/sql_patches.rb:160:in 'exec'
/home/user/.rvm/gems/ruby-2.1.1/gems/rack-mini-profiler-0.9.1/lib/patches/sql_patches.rb:160:in 'async_exec'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:815:in 'block in exec_no_cache'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:373:in 'block in log'
/home/user/.rvm/gems/ruby-2.1.1/gems/activesupport-4.1.0/lib/active_support/notifications/instrumenter.rb:20:in 'instrument'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:367:in 'log'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:815:in 'exec_no_cache'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:137:in 'exec_query'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:663:in 'enable_extension'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:649:in 'block in method_missing'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:621:in 'block in say_with_time'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:621:in 'say_with_time'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:641:in 'method_missing'
/home/user/rails/bdfzer-sso/db/migrate/20140405014358_set_up_hstore.rb:3:in 'change'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:595:in 'exec_migration'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:579:in 'block (2 levels) in migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:578:in 'block in migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:294:in 'with_connection'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:577:in 'migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:752:in 'migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:992:in 'block in execute_migration_in_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:1038:in 'block in ddl_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:211:in 'block in transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:219:in 'within_new_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:211:in 'transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/transactions.rb:208:in 'transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:1038:in 'ddl_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:991:in 'execute_migration_in_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:953:in 'block in migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:949:in 'each'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:949:in 'migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:807:in 'up'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:785:in 'migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/railties/databases.rake:34:in 'block (2 levels) in <top (required)>'
/home/user/.rvm/gems/ruby-2.1.1/bin/ruby_executable_hooks:15:in 'eval'
/home/user/.rvm/gems/ruby-2.1.1/bin/ruby_executable_hooks:15:in '<main>'
ActiveRecord::StatementInvalid: PG::UndefinedFile: ERROR:  could not open extension control file "/usr/share/postgresql/9.1/extension/hstore.control": No such file or directory
: CREATE EXTENSION IF NOT EXISTS "hstore"
/home/user/.rvm/gems/ruby-2.1.1/gems/rack-mini-profiler-0.9.1/lib/patches/sql_patches.rb:160:in 'exec'
/home/user/.rvm/gems/ruby-2.1.1/gems/rack-mini-profiler-0.9.1/lib/patches/sql_patches.rb:160:in 'async_exec'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:815:in 'block in exec_no_cache'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:373:in 'block in log'
/home/user/.rvm/gems/ruby-2.1.1/gems/activesupport-4.1.0/lib/active_support/notifications/instrumenter.rb:20:in 'instrument'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:367:in 'log'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:815:in 'exec_no_cache'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:137:in 'exec_query'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:663:in 'enable_extension'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:649:in 'block in method_missing'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:621:in 'block in say_with_time'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:621:in 'say_with_time'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:641:in 'method_missing'
/home/user/rails/bdfzer-sso/db/migrate/20140405014358_set_up_hstore.rb:3:in 'change'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:595:in 'exec_migration'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:579:in 'block (2 levels) in migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:578:in 'block in migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:294:in 'with_connection'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:577:in 'migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:752:in 'migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:992:in 'block in execute_migration_in_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:1038:in 'block in ddl_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:211:in 'block in transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:219:in 'within_new_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:211:in 'transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/transactions.rb:208:in 'transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:1038:in 'ddl_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:991:in 'execute_migration_in_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:953:in 'block in migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:949:in 'each'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:949:in 'migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:807:in 'up'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:785:in 'migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/railties/databases.rake:34:in 'block (2 levels) in <top (required)>'
/home/user/.rvm/gems/ruby-2.1.1/bin/ruby_executable_hooks:15:in 'eval'
/home/user/.rvm/gems/ruby-2.1.1/bin/ruby_executable_hooks:15:in '<main>'
PG::UndefinedFile: ERROR:  could not open extension control file "/usr/share/postgresql/9.1/extension/hstore.control": No such file or directory
/home/user/.rvm/gems/ruby-2.1.1/gems/rack-mini-profiler-0.9.1/lib/patches/sql_patches.rb:160:in 'exec'
/home/user/.rvm/gems/ruby-2.1.1/gems/rack-mini-profiler-0.9.1/lib/patches/sql_patches.rb:160:in 'async_exec'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:815:in 'block in exec_no_cache'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:373:in 'block in log'
/home/user/.rvm/gems/ruby-2.1.1/gems/activesupport-4.1.0/lib/active_support/notifications/instrumenter.rb:20:in 'instrument'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:367:in 'log'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:815:in 'exec_no_cache'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:137:in 'exec_query'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:663:in 'enable_extension'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:649:in 'block in method_missing'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:621:in 'block in say_with_time'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:621:in 'say_with_time'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:641:in 'method_missing'
/home/user/rails/bdfzer-sso/db/migrate/20140405014358_set_up_hstore.rb:3:in 'change'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:595:in 'exec_migration'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:579:in 'block (2 levels) in migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:578:in 'block in migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:294:in 'with_connection'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:577:in 'migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:752:in 'migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:992:in 'block in execute_migration_in_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:1038:in 'block in ddl_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:211:in 'block in transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:219:in 'within_new_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:211:in 'transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/transactions.rb:208:in 'transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:1038:in 'ddl_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:991:in 'execute_migration_in_transaction'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:953:in 'block in migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:949:in 'each'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:949:in 'migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:807:in 'up'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/migration.rb:785:in 'migrate'
/home/user/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/railties/databases.rake:34:in 'block (2 levels) in <top (required)>'
/home/user/.rvm/gems/ruby-2.1.1/bin/ruby_executable_hooks:15:in 'eval'
/home/user/.rvm/gems/ruby-2.1.1/bin/ruby_executable_hooks:15:in '<main>'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)

Depois de alguma pesquisa, encontrei uma postagem no SO indicando que posso executar

sudo apt-get install postgresql-contrib-9.1

Mas então o que eu tenho é

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package postgresql-contrib-9.1 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
  postgresql-9.1

E: Package 'postgresql-contrib-9.1' has no installation candidate