When you get an error like this:
Invalid gemspec in [/opt/www/foo-project.makandra.de/shared/bundle/ruby/1.8/specifications/carrierwave-0.6.2.gemspec]: Illformed requirement ["#<YAML::Syck::DefaultKey:0x7fda6f84d2e8> 1.1.4"]
... the machine's Rubygems needs to be updated.
/usr/lib/ruby/gems/1.8/gems/your-broken-gem
and /usr/lib/ruby/gems/1.8/specifications/your-broken-gem
gem update --system
shared/bundle
)