Should fix #525.
Pass the correct arity to #each in Enumerable#find_index.
Don't run the spec in 1.8 mode.
Ahh, I forgot that the specs will be run in 1.8 mode as well. Sorry, I should've caught that earlier, but for some reason, the extended test suite fails on my machine (even on master, which seems to be passing on Travis), so I couldn't run it before submitting this.
I feel that the spec should go to RubySpec.
I cherry-picked sluukkonen/jruby@b38990d to the master as de1abd0.
I am closing for accounting that this was fixed for 1.7.3. We would still love for you to submit this fixed behavior as a spec to the rubyspec project (pretty please) :)