Work around weird rubinius issue on travis.
Work around weird rubinius issue on travis.

http://travis-ci.org/#!/myronmarston/vcr/jobs/1443142/L128
nishanbose/vcr,ihassin/vcr,intfrr/vcr,davidbebb/vcr,allyapp/vcr,irfanah/vcr,Shopify/vcr,chriswoodrich/vcr,davidbebb/vcr,myronmarston/vcr,ihassin/vcr,Shopify/vcr,asymmetric/vcr,chriswoodrich/vcr,ZmagoD/vcr,intfrr/vcr,allyapp/vcr,mcfiredrill/vcr,mcfiredrill/vcr,cemo/vcr,myronmarston/vcr,irfanah/vcr,ZmagoD/vcr,cemo/vcr,asymmetric/vcr,nishanbose/vcr