Nokogiri Compilation Problems
Problems when running ./setup.sh on Mac OS with Nokogiri
What worked (09/13/2018, Mac OS 10.13.6, High Sierra)
brew update
brew install libxml2
bundle config build.nokogiri --use-system-libraries \
--with-xml2-include=$(brew --prefix libxml2)/include/libxml2
bundle install
Source: http://www.nokogiri.org/tutorials/installing_nokogiri.html#install_with_system_libraries