Brew still using 1.8 ruby verison. but OSX 10.10 ship with 2.0.0 so symoblinking for now.
$ sudo mkdir -p /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin
$ sudo ln -s /usr/bin/ruby /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
$ brew update
Make sure using OSX10.10 compiler, to get brew working.
$ sudo xcode-select -switch /Applications/Xcode6-Beta.app/Contents/Developer/
$ RVM get stable && rvm install ruby-2.0.0
#Caveat For ruby 1.9.3 it might be a bit tricky. make sure using the old complier otherwise you might have Error : linking miniruby internal:prelude:1: [BUG] Segmentation fault
$ sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer/
$ rvm install ruby-1.9.3 --with-gcc=clang
#Zsh in iTerm2
iTerm2 zsh might have problem with your local envs path and your git pull/stash might be broken.
To fix this, please in your iTerm2 Profile add
/bin/bash -c /bin/zsh
Then your git pull/stash etc should be working.
#Enjoy!