Demonstate issue with wonky constants on 1.9.2

I'm expecting this to fail, the reason why the spec is a new file is that 1.9.2's issue with wonky constants seems to stem from the first `instance_exec` not  the last, so having this inside an existing example group 
doesn't cause the bug to occur.

See #1697 

/cc @myronmarston
Since this is an ugly hack for an old version of ruby that is no longer maintained, I'd like for this hack to only apply to that version.  In the tests you can define a special version of `have_class_const` for 1.9.2.