spec: do not check for /usr/bin not to be writable when running as root.
spec: do not check for /usr/bin not to be writable when running as root.

This test would fail on default Gentoo installs as the package is
executed as root.

seanlinsley/bundler,joshsoftware/bundler,EthanK28/bundler,mattbrictson/bundler-1,robinboening/bundler,Elffers/bundler,Eric-Guo/bundler,e2/bundler,zhangkuaiji/bundler,smlance/bundler,cdwort/bundler,nju520/bundler,mattbrictson/bundler-1,lmtim/bundler,chef/bundler,wenderjean/bundler,schaary/bundler,CorainChicago/bundler,suhastech/bundler,gregkare/bundler,Wirachmat/bundler,Elffers/bundler,kohgpat/bundler,1337807/bundler,frsyuki/bundler,sideci-sample/sideci-sample-bundler,asutoshpalai/bundler,cstrahan/bundler,philnash/bundler,robinboening/bundler,anil826/bundler,steved/bundler,EthanK28/bundler,simplybusiness/bundler,asymmetric/bundler,Teino1978-Corp/Teino1978-Corp-bundler,tgxworld/bundler,PG-kura/bundler,mpapis/bundler,agis-/bundler,philnash/bundler,masarakki/bundler,haocafes/bundler,seanlinsley/bundler,ximus/bundler,ximus/bundler,carpodaster/bundler,pjump/bundler,christer155/bundler,Wirachmat/bundler,patvice/bundler,suhastech/bundler,TimMoore/bundler,tgxworld/bundler,roseweixel/bundler,chulkilee/bundler,ngpestelos/bundler,haonaturel/bundler,CorainChicago/bundler,haonature888/bundler,twcctz500000/bundler,carpodaster/bundler,gregkare/bundler,masarakki/bundler,ligi/bundler,nju520/bundler,simplybusiness/bundler,elovelan/bundler,EasonYi/bundler,patvice/bundler,jingweno/bundler,chulkilee/bundler,dilumnavanjana/bundler,asutoshpalai/bundler,pivotal-cf-experimental/bundler,christer155/bundler,vemmaverve/bundler,davydovanton/bundler,mdorrance/bundler,ligi/bundler,PG-kura/bundler,mdorrance/bundler,agis-/bundler,byroot/bundler,elovelan/bundler,frsyuki/bundler,kohgpat/bundler,danimashu/bundler,pjump/bundler,neslom/bundler,bundler/bundler,mvz/bundler,h4ck3rm1k3/bundler,asymmetric/bundler,danimashu/bundler,RochesterinNYC/bundler,chef/bundler,JuanitoFatas/bundler,pivotal-cf-experimental/bundler,roseweixel/bundler,haonature/bundler,jasonkarns/bundler,rkh/bundler,jaym/bundler,davydovanton/bundler,zhangkuaiji/bundler,lmtim/bundler,jaym/bundler,jingweno/bundler,AiyionPrime/bundler,Eric-Guo/bundler,TimMoore/bundler,bronzdoc/bundler,dilumnavanjana/bundler,anil826/bundler,cstrahan/bundler,mpapis/bundler,cdwort/bundler,bronzdoc/bundler,schaary/bundler,EasonYi/bundler,h4ck3rm1k3/bundler,jasonkarns/bundler,bundler/bundler,gentoo/bundler,ngpestelos/bundler,sideci-sample/sideci-sample-bundler,joshsoftware/bundler,mvz/bundler,byroot/bundler,AiyionPrime/bundler,ipmobiletech/bundler,eagletmt/bundler,wenderjean/bundler,RochesterinNYC/bundler,neslom/bundler,Teino1978-Corp/Teino1978-Corp-bundler,ipmobiletech/bundler,steved/bundler,r7kamura/bundler,smlance/bundler