ruby-on-rails-3 - Rails 3: 初期化されていない定数 IRB::ReadlineInputMethod::Heroku の Readline (NameError)

Question

Rails 3.2.13 に更新して以来、heroku rails コンソールを起動できませんでした。サーバーは正常に動作していますが、コンソールを実行しようとすると、次のエラーが発生します。

Loading production environment (Rails 3.2.13)
/app/vendor/bundle/ruby/1.9.1/gems/aws-s3-0.6.3/lib/aws/s3/extensions.rb:212:in `const_missing_from_s3_library': uninitialized constant IRB::ReadlineInputMethod::Readline (NameError)
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/input-method.rb:113:in `gets'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb.rb:139:in `block (2 levels) in eval_input'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb.rb:273:in `signal_status'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb.rb:138:in `block in eval_input'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:188:in `call'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:188:in `buf_input'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:103:in `getc'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/slex.rb:205:in `match_io'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/slex.rb:75:in `match'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:286:in `token'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:262:in `lex'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:233:in `block (2 levels) in each_top_level_statement'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `loop'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `block in each_top_level_statement'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `catch'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `each_top_level_statement'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb.rb:155:in `eval_input'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb.rb:70:in `block in start'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb.rb:69:in `catch'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb.rb:69:in `start'
    from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/commands/console.rb:47:in `start'
    from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/commands/console.rb:8:in `start'
    from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/commands.rb:41:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'

何が起こっている？ありがとう！