only warn once about plugin injection in rails 3
only warn once about plugin injection in rails 3

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pack-ruby,jumptvs/BP_Ruby,schu/buildpack-testing,Jonty/ruby-buildpack,jonasoberschweiber/heroku-buildpack-ruby,aarongray/heroku-buildpack-ruby,CPPWind/ruby-buildpack,hixi/heroku-buildpack-ruby,phusion/heroku-buildpack-ruby,dlorson/gentle-buildpack,engineyard/heroku-buildpack-ruby,cloudfoundry/ruby-buildpack,orlando/heroku-buildpack-ruby,guidance-guarantee-programme/heroku-buildpack-princexml-old,musicglue/heroku-buildpack-ruby,takii/db2rubybuildpack,mattmanning/heroku-buildpack-ruby-jekyll,Dim25/heroku-buildpack-ruby-GSL,stolt45/heroku-buildpack-ruby-with-sqlite3,cordata/heroku-buildpack-ruby,Micka33/heroku-buildpack-ruby-liblua,trumaker/heroku-buildpack-turbo-sprockets,orenyk/heroku-buildpack-ruby,redhotvengeance/heroku-buildpack-deep-thought,allomov/fat-free-heroku-buildpack-ruby,packetmonkey/heroku-buildpack-ruby,fcruxen/ruby-buildpack,amaltson/heroku-buildpack-ruby,space150/heroku-buildpack-ruby,DyegoCosta/heroku-buildpack-ruby,jeremyvdw/heroku-buildpack-ruby-jekyll,cmaggard/heroku-buildpack-turbo-sprockets,zidekmat/buildpack-ruby,phusion/heroku-buildpack-ruby,cloudn/buildpack-ruby,erintherad/heroku-buildpack-ruby,Dim25/heroku-buildpack-ruby-GSL,codykrieger/heroku-buildpack-jekyll,DouglasAllen/heroku-buildpack-ruby,amaltson/heroku-buildpack-ruby,tenjikinc/heroku-buildpack-ruby,jayshreeanand/heroku-buildpack-ruby,qnyp/heroku-buildpack-ruby-bower,Genius/heroku-buildpack-ruby,ericboehs/heroku-buildpack-ruby,takii/db2rubybuildpack,trumaker/heroku-buildpack-turbo-sprockets,cloudfoundry/ruby-buildpack,fcruxen/ruby-buildpack,ChefSteps/heroku-buildpack-ruby,tdenovan/heroku-buildpack-ruby,tpope/heroku-buildpack-ruby-tpope,qnyp/heroku-buildpack-ruby-bower,makifund/heroku-buildpack-ruby,fcruxen/ruby-buildpack,simonnordberg/heroku-buildpack-ruby,beydogan/ruby-buildpack,jonseaberg/heroku-buildpack-turbo-sprockets,musicglue/heroku-buildpack-ruby,gls1/heroku-buildpack-ruby-pdftk-new,schu/buildpack-testing,pietrop/heroku-buildpack-ruby,Jonty/ruby-buildpack,ascot21/heroku-buildpack-turbo-sprockets,bskyb-commerce/ruby-buildpack,DyegoCosta/heroku-buildpack-ruby,simonnordberg/heroku-buildpack-ruby,phusion/heroku-buildpack-ruby,d-reinhold/cf-buildpack-ruby,takii/heroku-buildpack-ruby,mrhenry/heroku-buildpack-ruby,icelab/heroku-buildpack-ruby,ndbroadbent/heroku-buildpack-turbo-sprockets,sky-uk/ruby-buildpack,ltrademark/heroku-buildpack-ruby,bskyb-commerce/help-heroku-buildpack,tpope/heroku-buildpack-ruby-tpope,CPPWind/ruby-buildpack,dieze/heroku-buildpack-ruby-hooks,tomwolfe/heroku-buildpack-gsl-ruby,markaschneider/heroku-buildpack-ruby-ffmpeg-sox,fcruxen/ruby-buildpack,samfrench/heroku-buildpack-ruby,d-reinhold/cf-buildpack-ruby,electricobjects/heroku-buildpack-ruby,thewebguy/heroku-buildpack-ruby-ffmpeg-libsndfile,cloudn/buildpack-ruby,daltonrenaldo/heroku-buildpack-ruby,leonardykris/mos-ruby-buildpack,HYPERHYPER/heroku-buildpack-ruby,engineyard/heroku-buildpack-ruby,markaschneider/heroku-buildpack-ruby-ffmpeg-sox,fgbreel/heroku-buildpack-ruby,zunda/heroku-buildpack-ruby,diasks2/heroku-buildpack-mecab,mattwalters/heroku-buildpack-ruby,moneyadviceservice/heroku-buildpack-ruby-bowndler,bskyb-commerce/ruby-buildpack,iamjarvo/ruby-buildpack,zidekmat/buildpack-ruby,shuber/heroku-buildpack-ruby,gls1/heroku-buildpack-ruby-pdftk,catalyzeio/buildpack-ruby,schu/heroku-buildpack-ruby,hpcloud/ruby-buildpack,instacart/heroku-buildpack-ruby,iamjarvo/ruby-buildpack,pilotcreative/heroku-buildpack-ruby,scottatron/moc-buildpack,erintherad/heroku-buildpack-ruby,DouglasAllen/heroku-buildpack-ruby,codykrieger/heroku-buildpack-jekyll,jumptvs/BP_Ruby,ericroberts/heroku-buildpack-ruby,Micka33/heroku-buildpack-ruby-liblua,stefansundin/heroku-buildpack-ruby,donnykurnia/heroku-buildpack-ruby,teodor-pripoae/heroku-buildpack-ruby,takii/db2rubybuildpack,sky-uk/ruby-buildpack,diasks2/heroku-buildpack-mecab,hixi/heroku-buildpack-ruby,takii/db2rubybuildpack,ChefSteps/heroku-buildpack-ruby,takii/heroku-buildpack-ruby,dleavitt/heroku-buildpack-ruby,Jonty/ruby-buildpack,pilotcreative/heroku-buildpack-ruby,derrek/heroku-buildpack-ruby,pietrop/heroku-buildpack-ruby,jonasoberschweiber/heroku-buildpack-ruby,d-reinhold/cf-buildpack-ruby,heroku/heroku-buildpack-ruby,reesio/heroku-buildpack-ruby,HYPERHYPER/heroku-buildpack-ruby,Git-Host/prelang-buildpack,0x00evil/heroku-buildpack-ruby,ablease/custom-buildpack,awebneck/heroku-buildpack-canvas,hellojustin/heroku-buildpack-custom-ruby,schu/heroku-buildpack-ruby,tdenovan/heroku-buildpack-ruby,crdschurch/heroku-buildpack-ruby,bellycard/heroku-buildpack-ruby,michaelphines/alexa-nest,gls1/heroku-buildpack-ruby-pdftk,ibmdb/db2rubybuildpack,righi/instacart-heroku-buildpack,qstream/heroku-buildpack-ruby,jumptvs/BP_Ruby,ablease/custom-buildpack,orlando/heroku-buildpack-ruby