Fix gem_helper_spec.rb when run with git 2.0.
Fix gem_helper_spec.rb when run with git 2.0.

Git now errors out if you haven't set a default push behavior.

sideci-sample/sideci-sample-bundler,mattbrictson/bundler-1,simplybusiness/bundler,dilumnavanjana/bundler,chulkilee/bundler,mvz/bundler,christer155/bundler,EasonYi/bundler,christer155/bundler,robinboening/bundler,tgxworld/bundler,philnash/bundler,asymmetric/bundler,mpapis/bundler,simplybusiness/bundler,patvice/bundler,zhangkuaiji/bundler,patvice/bundler,h4ck3rm1k3/bundler,TimMoore/bundler,bronzdoc/bundler,elovelan/bundler,Teino1978-Corp/Teino1978-Corp-bundler,chulkilee/bundler,danimashu/bundler,bundler/bundler,Eric-Guo/bundler,Elffers/bundler,neslom/bundler,lmtim/bundler,e2/bundler,jaym/bundler,PG-kura/bundler,bronzdoc/bundler,smlance/bundler,tgxworld/bundler,asutoshpalai/bundler,masarakki/bundler,mattbrictson/bundler-1,CorainChicago/bundler,joshsoftware/bundler,lmtim/bundler,CorainChicago/bundler,suhastech/bundler,anil826/bundler,smlance/bundler,mdorrance/bundler,AiyionPrime/bundler,asutoshpalai/bundler,suhastech/bundler,neslom/bundler,EthanK28/bundler,ngpestelos/bundler,nju520/bundler,seanlinsley/bundler,ngpestelos/bundler,asymmetric/bundler,robinboening/bundler,masarakki/bundler,byroot/bundler,schaary/bundler,RochesterinNYC/bundler,nju520/bundler,chef/bundler,davydovanton/bundler,ximus/bundler,chef/bundler,gregkare/bundler,roseweixel/bundler,danimashu/bundler,pivotal-cf-experimental/bundler,kohgpat/bundler,mdorrance/bundler,cdwort/bundler,cstrahan/bundler,dilumnavanjana/bundler,carpodaster/bundler,Eric-Guo/bundler,Wirachmat/bundler,frsyuki/bundler,pjump/bundler,gregkare/bundler,h4ck3rm1k3/bundler,Wirachmat/bundler,ligi/bundler,philnash/bundler,wenderjean/bundler,Elffers/bundler,sideci-sample/sideci-sample-bundler,jingweno/bundler,ximus/bundler,frsyuki/bundler,wenderjean/bundler,jasonkarns/bundler,pivotal-cf-experimental/bundler,EthanK28/bundler,schaary/bundler,jaym/bundler,RochesterinNYC/bundler,AiyionPrime/bundler,PG-kura/bundler,mpapis/bundler,anil826/bundler,byroot/bundler,Teino1978-Corp/Teino1978-Corp-bundler,EasonYi/bundler,ipmobiletech/bundler,kohgpat/bundler,TimMoore/bundler,agis-/bundler,agis-/bundler,jasonkarns/bundler,elovelan/bundler,roseweixel/bundler,ligi/bundler,seanlinsley/bundler,steved/bundler,cstrahan/bundler,carpodaster/bundler,davydovanton/bundler,mvz/bundler,steved/bundler,joshsoftware/bundler,cdwort/bundler,pjump/bundler,bundler/bundler,jingweno/bundler,zhangkuaiji/bundler,ipmobiletech/bundler