WWW::Mechanize and Rails console not playing well

I can run this code just fine in irb, but when I run it in rails script/console, I get an error:

res = agent.submit(search_form, search_form.buttons.first)

ArgumentError: one hash required         from /home/jwoods/NetBeansProjects/activista/vendor/rails/ actionmailer/lib/../../actionpack/lib/../../activesupport/lib/ active_support/core_ext/string/interpolation.rb:85:in `%'         from /usr/lib/ruby/1.8/webrick/httputils.rb:352:in `_escape'         from /usr/lib/ruby/1.8/webrick/httputils.rb:352:in `gsub'         from /usr/lib/ruby/1.8/webrick/httputils.rb:352:in `_escape'         from /usr/lib/ruby/1.8/webrick/httputils.rb:370:in `escape_form'         from /usr/lib/ruby/1.8/www/mechanize/util.rb:9:in `build_query_string'         from /usr/lib/ruby/1.8/www/mechanize/util.rb:6:in `map'         from /usr/lib/ruby/1.8/www/mechanize/util.rb:6:in `build_query_string'         from /usr/lib/ruby/1.8/www/mechanize/form.rb:199:in `request_data'         from /usr/lib/ruby/1.8/www/mechanize.rb:387:in `post_form'         from /usr/lib/ruby/1.8/www/mechanize.rb:331:in `submit'         from (irb):23

Here's the code: #!/usr/local/bin/ruby require 'rubygems' require 'mechanize' require 'logger' require 'uri' require 'net/http'

agent = WWW::Mechanize.new { |a| a.log = Logger.new("mech.log") } agent.user_agent_alias = 'Mac Safari' page = agent.get('Who Represents Me?’) search_form = page.form_with(:name => "AddressForm") search_form.field_with(:name => "Address1").value = "501 W 26th St, Apt 110" search_form.field_with(:name => "City").value = "Austin" search_form.field_with(:name => "ZipCode").value = "78705" search_form.field_with(:name => "DistrictType").options[0].select res = agent.submit(search_form, search_form.buttons.first)

It should return a Mechanize page object.

And no, that's no longer my address.

What is this interpolation core extension? Why is that causing a problem? Can I disable it for this lib I'm working on?

Thanks so much, John