Fix FakeWeb error extension so that it works on JRuby.
Fix FakeWeb error extension so that it works on JRuby.

(I have no idea why this wasn't working on JRuby, but it wasn't, and this fixes it).
benjaminoakes/vcr,chriswoodrich/vcr,travis-repos/vcr,mcfiredrill/vcr,myronmarston/vcr,cemo/vcr,davidbebb/vcr,nishanbose/vcr,allyapp/vcr,nishanbose/vcr,ZmagoD/vcr,Shopify/vcr,Shopify/vcr,chriswoodrich/vcr,ZmagoD/vcr,ihassin/vcr,irfanah/vcr,myronmarston/vcr,asymmetric/vcr,asymmetric/vcr,ihassin/vcr,irfanah/vcr,cemo/vcr,davidbebb/vcr,intfrr/vcr,intfrr/vcr,mcfiredrill/vcr,allyapp/vcr