after gem update 2011-02-01 (most likely: rubygems-update-1.4.2 -> 1.5.0)

gistfile1.txt

$ ./script/server 
=> Booting Mongrel
=> Rails 2.3.5 application starting on http://0.0.0.0:3000
/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/gem_dependency.rb:119:in `requirement': undefined local variable or method `version_requirements' for #<Rails::GemDependency:0xf6e64a78> (NameError)
        from /usr/local/lib/site_ruby/1.8/rubygems.rb:254:in `activate'
        from /usr/local/lib/site_ruby/1.8/rubygems.rb:1204:in `gem'
        from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/gem_dependency.rb:73:in `add_load_paths'
        from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:301:in `add_gem_load_paths'
        from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:301:in `each'
        from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:301:in `add_gem_load_paths'
        from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:132:in `process'
        from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:113:in `send'
        from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:113:in `run'
        from ** config/environment.rb:13
        from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:29:in `gem_original_require'
        from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:29:in `require'
        from /usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:156:in `require'
        from /usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:521:in `new_constants_in'
        from /usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:156:in `require'
        from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/commands/server.rb:84
        from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:29:in `gem_original_require'
        from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:29:in `require'
        from ./script/server:3

Four years later, it helped me. Thanks!