Add temporary workaround for failing build on Ruby 1.8.7 Rubygems broke builds on Ruby 1.8.7:
Add temporary workaround for failing build on Ruby 1.8.7
Rubygems broke builds on Ruby 1.8.7:

travis-ci/travis-ci#1793
rubygems/rubygems#763

This patch is a temporary workaround until rubygems is updated.
iguchi1124/rspec-core,edwardpark/rspec-core,edwardpark/rspec-core,danascheider/rspec-core,h4ck3rm1k3/rspec-core,a-suenami/rspec-core,arronmabrey/rspec-core,Teino1978-Corp/Teino1978-Corp-rspec-core,rspec/rspec-core,irfanah/rspec-core,eugeneius/rspec-core,azbshiri/rspec-core,dg-ratiodata/rspec-core,azbshiri/rspec-core,behnaaz/rspec-core,rspec/rspec-core,danascheider/rspec-core,azbshiri/rspec-core,eugeneius/rspec-core,dg-ratiodata/rspec-core,pandabrand/rspec-core,iguchi1124/rspec-core,rspec/rspec-core,xmik/rspec-core,urbanautomaton/rspec-core,eugeneius/rspec-core,avantcredit/rspec-core,xmik/rspec-core,a-suenami/rspec-core,dg-ratiodata/rspec-core,SoldierCoder/rspec-core,maclover7/rspec-core,avantcredit/rspec-core,SoldierCoder/rspec-core,a-suenami/rspec-core,iguchi1124/rspec-core,maclover7/rspec-core,pandabrand/rspec-core,irfanah/rspec-core,danascheider/rspec-core,yaoshipu/rspec-core,Teino1978-Corp/Teino1978-Corp-rspec-core,maclover7/rspec-core,behnaaz/rspec-core,urbanautomaton/rspec-core,leg100/rspec-core,Teino1978-Corp/Teino1978-Corp-rspec-core,arronmabrey/rspec-core,yaoshipu/rspec-core,edwardpark/rspec-core,irfanah/rspec-core,leg100/rspec-core,arronmabrey/rspec-core,urbanautomaton/rspec-core,xmik/rspec-core,avantcredit/rspec-core,yaoshipu/rspec-core,SoldierCoder/rspec-core,h4ck3rm1k3/rspec-core,behnaaz/rspec-core,leg100/rspec-core,pandabrand/rspec-core,h4ck3rm1k3/rspec-core