I have recently reinstalled ruby 2.1.2 like so since I wanted to install a gem (ruby-debug-ide)
ruby-debug-ide
sudo rvm reinstall 2.1.2 --disable-binary --with
None of all this worked for me. I am using osx sierra. This what worked for me.
ln -s /usr/local/opt/readline/lib/libreadline.7.0.dylib /usr/local/opt/readline/lib/libreadline.6.dylib
Hope this helps someone out there.