Hi Joerg,
This is a real bug and it has been solved. See the following thread.
http://groups.google.com/group/rubyonrails-core/browse_thread/thread/73f21c47d114b88e
To solve the problem apply the patch on:
http://rails.lighthouseapp.com/projects/8994-ruby-on-rails/tickets/1464
The shortcut way is to add a line to:
/usr/lib/ruby/gems/1.8/gems/rails-2.2.2/lib/rails/gem_dependency.rb
def dependencies
return [] if framework_gem?
return [] if specification.nil? # <= THE NEW LINE
all_dependencies = specification.dependencies.map do |dependency|
Hopefully soon there will be an updated gem.
Have fun,
Sander