Can you upgrade your require version of libxml for a compatibility with ruby 1.9.3 (preview at this time)
Because installed libyml-ruby version 1.X doesn't work. And it's fix with version 2.1
Pull request from (ehutzelman/happymapper) resolve this bug : https://github.com/ehutzelman/happymapper
FYI, you can install the mentioned repo as a plugin and do this in your gemfile:
gem "happymapper", "0.3.2", :path => 'vendor/plugins'
Which will get you by for now.
The bug is fixed with the pull request from ehutzelman, but any date for a release ?
Very thanks for this release