Found the following while making sure Net::SSH works with 1.8.4:

   irb(main):001:0> Struct.new(:valid?).new.valid?
   NoMethodError: undefined method `valid?' for #<struct #<Class: 
0x535994> :valid?=nil>
         from (irb):1

This worked in 1.8.2, at least. Is this an intentional change? (This  
only bites me in the unit tests for Net::SSH, and I can easily work  
around it, just wanted to make sure problem this was known.)

- Jamis