emerging vim pulls in ruby:1.9 if only ruby:2.0 is installed. I have modified vim.eclass locally to accept 2.0 and it seems to work just fine. Changing ruby? ( || ( dev-lang/ruby:1.9 dev-lang/ruby:1.8 ) )" to ruby? ( || ( dev-lang/ruby:2.0 dev-lang/ruby:1.9 dev-lang/ruby:1.8 ) )" on lines 99 and 105 of vim.eclass is all that is needed.
Added to >=7.4 in CVS.