Cannot load backend http

[robruma]

While running any hiera query, this warning is generated:
WARN: 2014-08-19 21:47:40 -0400: Cannot load backend http: cannot load such file -- hiera/backend/http_backend
and no data is returned from the http backend.
If I make a symlink like so...
# ln -s /var/opt/lib/pe-puppet/lib/hiera/backend/http_backend.rb /opt/puppet/lib/ruby/site_ruby/1.9.1/hiera/backend/http_backend.rb
hiera_http works as expected and returns the correct data.
I'm using Puppet Enterprise 3.3.0 with pe-hiera 1.3.3 and pe-ruby 1.9.3
I also have ruby 1.8.7 installed on the system. Not sure if that would cause this behavior though.