mongoid at /Users/sergei/.rvm/gems/ruby-1.9.2-p290@pravdorub/bundler/gems/mongoid-e1a16d796d51 did not have a valid gemspec.
This prevents bundler from installing bins or native extensions, but that may not affect its functionality.
The validation message from Rubygems was:
["README.rdoc"] are not files

And indeed, there's no such file.