RedCloth 4.2.6 is broken on Mac OS X. It appears to be related to the case sensitive require fix. These steps expose and fix the problem on my machine.
$ ruby -v
ruby 1.8.7 (2009-12-24 patchlevel 248) [i686-darwin10.3.0], MBARI 0x6770, Ruby Enterprise Edition 2010.01
$ gem -v
1.3.7
$ cd ~
$ mkdir tmp-redcloth-test
$ cd tmp-redcloth-test
$ cat > Gemfile
source :rubygems
gem 'RedCloth', '4.2.6'
<ctrl-d>
$ bundle install --path gems
$ ruby -e"require 'rubygems'; require 'bundler/setup'; require 'RedCloth'"
-e:1:in `require': no such file to load -- RedCloth (LoadError)
from -e:1
$ REDCLOTH_PATH=`bundle show RedCloth` \
ruby -e "\
gemspec_file = File.join(ENV['REDCLOTH_PATH'], 'redcloth.gemspec')
gemspec = File.read(gemspec_file)
r = /s\.require_path.*/
gemspec = gemspec.sub(r, 's.require_paths = [\'lib\', \'lib/case_sensitive_require\', \'lib/lib/case_sensitive_require\']')
File.open(gemspec_file, 'w') { |f| f.puts(gemspec) }"
$ REDCLOTH_PATH=`bundle show RedCloth` \
ruby -e "\
gemfile_path = 'Gemfile'
gemfile = File.read(gemfile_path)
r = /'4\.2\.6'/
gemfile = gemfile.sub(r, ':path => \'' + ENV['REDCLOTH_PATH'] + '\'')
File.open(gemfile_path, 'w') { |f| f.puts(gemfile) }"
$ bundle install
$ ruby -e"require 'rubygems'; require 'bundler/setup'; require 'RedCloth'"
I have installed Bundler, but at the step "Use Bundler to install RedCloth," it fails for me. I get