require yaml even if rubygems has defined YAML
require yaml even if rubygems has defined YAML

fixes #2393, #2394

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