ironruby rake compile stack trace

gistfile1.txt

C:\Development\ironruby\Merlin\Main\Languages\Ruby>rake --tasks --trace
(in C:/Development/ironruby/Merlin/Main/Languages/Ruby)
rake aborted!
undefined method `join' for nil:NilClass
C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/gem_path_searcher.rb:96:in `lib_dirs_for'
C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/gem_path_searcher.rb:26:in `initialize'
C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/gem_path_searcher.rb:25:in `each'
C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/gem_path_searcher.rb:25:in `initialize'
C:/Ruby/lib/ruby/site_ruby/1.8/rubygems.rb:684:in `new'
C:/Ruby/lib/ruby/site_ruby/1.8/rubygems.rb:684:in `searcher'
C:/Ruby/lib/ruby/site_ruby/1.8/rubygems.rb:683:in `synchronize'
C:/Ruby/lib/ruby/site_ruby/1.8/rubygems.rb:683:in `searcher'
C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:34:in `require'
./context.rb:17
C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'
C:/Development/ironruby/Merlin/Main/Languages/Ruby/rakefile:18
C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:2359:in `load'
C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:2359:in `raw_load_rakefile'
C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:1993:in `load_rakefile'
C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:2044:in `standard_exception_handling'
C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:1992:in `load_rakefile'
C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:1976:in `run'
C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:2044:in `standard_exception_handling'
C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:1974:in `run'
C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.4/bin/rake:31
C:/ruby/bin/rake:19:in `load'
C:/ruby/bin/rake:19

C:\Development\ironruby\Merlin\Main\Languages\Ruby>