hpricot.

[hpricot + Rails 3.1] ArgumentError (wrong number of arguments (1 for 0))

We have a known issue with hpricot + Rails 3.1, This is a known caused by hpricot clobbering bundler's usage of String#to_xml. Please downgrade and/or remove hpricot and track resolution here:
https://github.com/hpricot/hpricot/issues/53

Our issue is here https://github.com/airbrake/airbrake/issues/24 ; which is caused by https://github.com/hpricot/hpricot/issues/53