Ampersands in POST data parses as Query String Separator

This can be reproduced with the following code:

class Foos < Application
  def bar
    self.logger.debug params.inspect
    ok
end

Then call:

client.post('/foos/bar', :key => "value&value2")

The interesting log part will reveal:

{:action => 'bar', :controller => 'foos', :key => 'value', :value2 => nil}

Ick.