If you get this error:
Cannot modify SafeBuffer in place ruby/1.8/gems/activesupport-3.0.9/lib/active_support/core_ext/string/output_safety.rb:119:in gsub!' ruby/1.8/xmlrpc/create.rb:54:in text'
You might need to upgrade haml, or if that doesn't help you need to convert the SafeBuffer to a String. In this case it's the parameters given to an XML-RPC call that need to be converted to strings:
In other words the solution is to update your gem or use .to_str.