Please check: I'm not really sure wether to use @@builder or options[:builder] in this place.
Could you please follow this up with a test case so that we don't re-introduce a regression? At the very least a comment above the line. I still don't understand why this patch helped, and under what circumstances. Then again, it is 7am :)
@justinfrench It seems there's a scoping/ context issue when using builder. When using navigasmic, builder is a reference to Navigasmic::HtmlNavigationBuilder:Class instead of Formtastic::FormBuilder. I'm not really sure why, because I don't know how exactly the mattr_accessor works. I thought it doesn't create instance accessors - as in many places @@builder instead of the accessor builder is used - and so I simply adjusted this call too. I'll investigate further and try to add a test case.
I'm working on this.