Server Error 500 when fetching rdoc gems

I am trying to run a bundle update on my Mac which has been upgraded to Lion.

It is consistently failing to fetch rdoc, with the following error.

/Users/anita/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/site_ruby/1.9.1/rubygems
/remote_fetcher.rb:215:in `fetch_http': bad response Internal Server Error 500 
(http://production.cf.rubygems.org/gems/rdoc-3.9.1.gem) (Gem::RemoteFetcher::FetchError)

Is this likely to be something I can fix, or is it a problem with rubygems or rdoc that I can expect to see clear itself?

Other gems are downloading and installing correctly. I don't directly call for rdoc in my Gemfile, but I have tried adding it with a specific (lower) version, and I get the same error. I also get the same error from a gem install rdoc.

Here are the contents of my gemfile:

source 'http://rubygems.org'

gem 'rails'     , '>=3.1.0.rc5'
gem 'sprockets', '>= 2.0.0.beta.10' 
gem 'mysql2'

gem 'rack-cache', :require => 'rack/cache'
gem 'dragonfly', '~>开发者_如何转开发;0.9.4'

# Asset template engines
gem 'sass'
gem 'coffee-script'
gem 'uglifier'

gem 'jquery-rails', '>= 1.0.3'
gem 'simple_form'
gem 'remotipart', "~> 0.4"
gem 'devise', '1.1.rc0'      
group :test do
  # Pretty printed test output
  gem 'turn', :require => false
end

All is OK if I use Rails 3.1.0.rc1, or rc2, or rc3. But they seem to have a problem (referenced here ) with sprockets. The recommendation is to go to rails 3.1.0rc5. It is when I try to do that (and at rc4) that I see the problem fetching rdoc. An alternative to rails 3.1.0rc5 is to use an earlier release of sprocket but I have had no luck with that either.

Could not find gem 'sprockets (= 2.0.0.beta.10)' in any of the gem sources listed in your Gemfile.

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I fixed a similar problem by upgrading to Rails 3.1.0rc6.