ruby on rails 3 - ruby_threadptr_data_type error

Question

I'm starting up a new rails app with the latest version of rails (3.1.3). Rails crashes when I try to start up the server. First I fixed this bug, and now I'm getting this one

ruby-debug-base19-0.11.25/lib/ruby_debug.so: undefined symbol: ruby_threadptr_data_type 

There's a discussion about this going on here, but I can't make enough sense of it to get things to work.

UPDATE

I updated the version of ruby-debug

gem 'ruby-debug-base19x', '~> 0.11.30.pre4'

and have now moved on to this error

linecache19-0.5.12/lib/trace_nums19.so: undefined symbol: ruby_current_thread

Answer 1

Ok, it turns out that both ruby-debug and linecache needed to be manually updated to the latest versions. These lines in my gemfile did the trick

gem 'linecache19', :git => 'git://github.com/mark-moseley/linecache'
gem 'ruby-debug-base19x', '~> 0.11.30.pre4'
gem 'ruby-debug19'

To run specs, you need to run bundle exec rspec -d spec