gistfile1.sh

[andrew_taylor@accounts-081-pt-uat host_app]$ bundle exec nokogiri -v
# Nokogiri (1.6.0)
    ---
    warnings: []
    nokogiri: 1.6.0
    ruby:
      version: 1.9.3
      platform: x86_64-linux
      description: ruby 1.9.3p125 (2012-02-16 revision 34643) [x86_64-linux]
      engine: ruby
    libxml:
      binding: extension
      source: packaged
      libxml2_path: /tmp/working/app/host_app/vendor/bundle/ruby/1.9.1/gems/nokogiri-1.6.0/ports/x86_64-redhat-linux/libxml2/2.8.0
      libxslt_path: /tmp/working/app/host_app/vendor/bundle/ruby/1.9.1/gems/nokogiri-1.6.0/ports/x86_64-redhat-linux/libxslt/1.1.26
      compiled: 2.8.0
      loaded: 2.8.0
[andrew_taylor@accounts-081-pt-uat host_app]$ mv /tmp/working /tmp/notworking

[andrew_taylor@accounts-081-pt-uat host_app]$ bundle exec nokogiri -v
WARNING: Nokogiri was built against LibXML version 2.8.0, but has dynamically loaded 2.7.6
# Nokogiri (1.6.0)
    ---
    warnings:
    - Nokogiri was built against LibXML version 2.8.0, but has dynamically loaded 2.7.6
    nokogiri: 1.6.0
    ruby:
      version: 1.9.3
      platform: x86_64-linux
      description: ruby 1.9.3p125 (2012-02-16 revision 34643) [x86_64-linux]
      engine: ruby
    libxml:
      binding: extension
      source: packaged
      libxml2_path: /tmp/working/app/host_app/vendor/bundle/ruby/1.9.1/gems/nokogiri-1.6.0/ports/x86_64-redhat-linux/libxml2/2.8.0
      libxslt_path: /tmp/working/app/host_app/vendor/bundle/ruby/1.9.1/gems/nokogiri-1.6.0/ports/x86_64-redhat-linux/libxslt/1.1.26
      compiled: 2.8.0
      loaded: 2.7.6

If you notice, when /tmp/working doesn't exist (ie when we deploy to a different box that we built on) the version loaded reverts to 2.7.6 which is the version we have installed system-wide from yum. I would expect that the libxml2_path was the path in ./vendor/bundle at the time of execution, not, at the time of build.