fix bundle install for ruby 1.8.7
fix bundle install for ruby 1.8.7

Bundler gets removed from the `$LOAD_PATH` for some reason in ruby 1.8.7.
This means we shouldn't try to require something from bundler here.

> Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native
> extension.
>
>        /home/hone/.rvm/rubies/ruby-1.8.7-p371/bin/ruby extconf.rb
> /home/hone/.rvm/rubies/ruby-1.8.7-p371/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:36:in
> `gem_original_require': no such file to load -- bundler/psyched_yaml
> (LoadError)
>         from
> /home/hone/.rvm/rubies/ruby-1.8.7-p371/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:36:in
> `require'
>         from
> /home/hone/Projects/heroku_work/heroku-buildpack-ruby/vendor/syck_hack.rb:15

cmaggard/heroku-buildpack-turbo-sprockets,ekaranto/rails4-bluemix-buildpack,jumptvs/BP_Ruby,Dim25/heroku-buildpack-ruby-GSL,mattmanning/heroku-buildpack-ruby-jekyll,Micka33/heroku-buildpack-ruby-liblua,CPPWind/ruby-buildpack,gls1/heroku-buildpack-ruby-pdftk-new,recursecenter/heroku-buildpack-ruby,DigitalInnovation/heroku-buildpack-mslabs,hixi/heroku-buildpack-ruby,ablease/custom-buildpack,crdschurch/heroku-buildpack-ruby,stolt45/heroku-buildpack-ruby-with-sqlite3,barakav/heroku-buildpack-ruby,dlorson/gentle-buildpack,jeremyvdw/heroku-buildpack-ruby-jekyll,tdenovan/heroku-buildpack-ruby,awebneck/heroku-buildpack-canvas,trumaker/heroku-buildpack-turbo-sprockets,orlando/heroku-buildpack-ruby,ericboehs/heroku-buildpack-ruby,engineyard/heroku-buildpack-ruby,wolfoo2931/heroku-buildpack-ruby-2a352ae,Nedomas/heroku-buildpack-ruby-minus-node-with-node-paths,takii/db2rubybuildpack,Git-Host/prelang-buildpack,blueapron/heroku-buildpack-ruby,pietrop/heroku-buildpack-ruby,HYPERHYPER/heroku-buildpack-ruby,ericboehs/heroku-buildpack-ruby,mperejda/heroku-buildpack-ruby,dtao/teeny-buildpack,rvizza/heroku-buildpack-gsl-ruby,lyoshenka/heroku-buildpack-ruby-jekyll,bskyb-commerce/ruby-buildpack,Altoros/ruby-buildpack,ActiveState/heroku-buildpack-ruby,d-reinhold/cf-buildpack-ruby,jumptvs/BP_Ruby,packetmonkey/heroku-buildpack-ruby,heroku/heroku-buildpack-ruby,sanemat/heroku-buildpack-ruby-tachikoma,Dim25/heroku-buildpack-ruby-GSL,jgable/buildpack-ruby-rack-setup-tasks,lemurheavy/heroku-buildpack-ruby,d-reinhold/cf-buildpack-ruby,bskyb-commerce/ruby-buildpack,progrium/heroku-buildpack-ruby,sanemat/heroku-buildpack-ruby-tachikoma,cloudn/buildpack-ruby,bskyb-commerce/ruby-buildpack,jeremyvdw/heroku-buildpack-ruby-jekyll,KoanHealth/heroku-buildpack-marvin-setup,hpcloud/heroku-buildpack-ruby,icelab/heroku-buildpack-ruby,aarongray/heroku-buildpack-ruby,moneyadviceservice/heroku-buildpack-ruby-bowndler,Altoros/ruby-buildpack,mattwalters/heroku-buildpack-ruby,lemurheavy/heroku-buildpack-ruby,simonnordberg/heroku-buildpack-ruby,fcruxen/ruby-buildpack,donnykurnia/heroku-buildpack-ruby,catalyzeio/buildpack-ruby,tpope/heroku-buildpack-ruby-tpope,AdStage/heroku-buildpack-ruby,amaltson/heroku-buildpack-ruby,mintybit/heroku-buildpack-ruby,takii/db2rubybuildpack,reesio/heroku-buildpack-ruby,Altoros/ruby-buildpack,jonseaberg/heroku-buildpack-turbo-sprockets,redhotvengeance/heroku-buildpack-deep-thought,righi/instacart-heroku-buildpack,ilpoldo/heroku-buildpack-ruby,mrhenry/heroku-buildpack-ruby,gls1/heroku-buildpack-ruby-pdftk,jgable/buildpack-ruby-rack-setup-tasks,leonardykris/mos-ruby-buildpack,0x00evil/heroku-buildpack-ruby,pilotcreative/heroku-buildpack-ruby,orenyk/heroku-buildpack-ruby,ekaranto/rails4-bluemix-buildpack,thewebguy/heroku-buildpack-ruby-ffmpeg-libsndfile,Scalingo/ruby-buildpack,ltrademark/heroku-buildpack-ruby,swipesense/heroku-buildpack-ruby,stolt45/heroku-buildpack-ruby-with-sqlite3,beydogan/ruby-buildpack,tomwolfe/heroku-buildpack-gsl-ruby,catalyzeio/buildpack-ruby,ilpoldo/heroku-buildpack-ruby,centresource/heroku-buildpack-turbo-sprockets-pmp-ffm,phusion/heroku-buildpack-ruby,travis-ci/heroku-buildpack-ruby,rowanoulton/heroku-buildpack-ruby,sky-uk/help-heroku-buildpack,DouglasAllen/heroku-buildpack-ruby,cloudControl/buildpack-ruby,Jonty/ruby-buildpack,qstream/heroku-buildpack-ruby,zunda/heroku-buildpack-ruby,dlorson/gentle-buildpack,barakav/heroku-buildpack-ruby,Genius/heroku-buildpack-ruby,schu/heroku-buildpack-ruby,cloudn/buildpack-ruby,mintybit/heroku-buildpack-ruby,shuber/heroku-buildpack-ruby,dieze/heroku-buildpack-ruby-hooks,ltrademark/heroku-buildpack-ruby,lemurheavy/heroku-buildpack-ruby,centresource/heroku-buildpack-turbo-sprockets-pmp-ffm,ibmdb/db2rubybuildpack,hatofmonkeys/ruby-testing-buildpack,ablease/custom-buildpack,zidekmat/buildpack-ruby,icelab/heroku-buildpack-ruby,Jonty/ruby-buildpack,space150/heroku-buildpack-ruby,gls1/heroku-buildpack-ruby-pdftk,ericroberts/heroku-buildpack-ruby,pkgr/buildpack-ruby-precise-old,reesio/heroku-buildpack-ruby,pietrop/heroku-buildpack-ruby,cordata/heroku-buildpack-ruby,michaelphines/alexa-nest,musicglue/heroku-buildpack-ruby,qnyp/heroku-buildpack-ruby-bower,hpcloud/ruby-buildpack,pilotcreative/heroku-buildpack-ruby,Jonty/ruby-buildpack,jasonlevens/heroku-buildpack-ruby,sky-uk/ruby-buildpack,davidjrice/heroku-buildpack-couchbase-ruby,cmaggard/heroku-buildpack-turbo-sprockets,diasks2/heroku-buildpack-mecab,hellojustin/heroku-buildpack-custom-ruby,iamjarvo/ruby-buildpack,erintherad/heroku-buildpack-ruby,stefansundin/heroku-buildpack-ruby,phusion/heroku-buildpack-ruby,anay/buildpack-ruby-with-oracle-jdk,fcruxen/ruby-buildpack,bwaite-jaroop/heroku-buildpack-ruby,instacart/heroku-buildpack-ruby,makifund/heroku-buildpack-ruby,davidjrice/heroku-buildpack-couchbase-ruby,CPPWind/ruby-buildpack,redhotvengeance/heroku-buildpack-deep-thought,andycroll/heroku-buildpack-jekyll,Micka33/heroku-buildpack-ruby-liblua,takii/heroku-buildpack-ruby,leonardykris/mos-ruby-buildpack,ablease/custom-buildpack,shuber/heroku-buildpack-ruby,allomov/fat-free-heroku-buildpack-ruby,lyoshenka/heroku-buildpack-ruby-jekyll,ibmdb/db2rubybuildpack,schu/heroku-buildpack-ruby,tpope/heroku-buildpack-ruby-tpope,pkgr/heroku-buildpack-ruby,blueapron/heroku-buildpack-ruby,rhomobile/heroku-buildpack-ruby,ndbroadbent/heroku-buildpack-turbo-sprockets,markaschneider/heroku-buildpack-ruby-ffmpeg-sox,thewebguy/heroku-buildpack-ruby-ffmpeg-libsndfile,swipesense/heroku-buildpack-ruby,dleavitt/heroku-buildpack-ruby,progrium/heroku-buildpack-ruby,allomov/fat-free-heroku-buildpack-ruby,rhomobile/heroku-buildpack-ruby,tenjikinc/heroku-buildpack-ruby,cloudControl/buildpack-ruby,fcruxen/ruby-buildpack,progrium/heroku-buildpack-ruby,samfrench/heroku-buildpack-ruby,jayshreeanand/heroku-buildpack-ruby,d-reinhold/cf-buildpack-ruby,Git-Host/prelang-buildpack,simonnordberg/heroku-buildpack-ruby,teodor-pripoae/heroku-buildpack-ruby,sky-uk/ruby-buildpack,bskyb-commerce/help-heroku-buildpack,gbenedict/heroku-buildpack-ruby,recursecenter/heroku-buildpack-ruby,ekaranto/rails4-bluemix-buildpack,pkgr/heroku-buildpack-ruby,hpcloud/ruby-buildpack,jasonlevens/heroku-buildpack-ruby,sstelfox/buildpack-ruby,zunda/heroku-buildpack-ruby,wolfoo2931/heroku-buildpack-ruby-2a352ae,zoomer/heroku-buildpack-ruby-bower,sky-uk/ruby-buildpack,ChefSteps/heroku-buildpack-ruby,codykrieger/heroku-buildpack-jekyll,righi/instacart-heroku-buildpack,orlando/heroku-buildpack-ruby,erintherad/heroku-buildpack-ruby,diasks2/heroku-buildpack-mecab,andycroll/heroku-buildpack-jekyll,tomwolfe/heroku-buildpack-gsl-ruby,cloudfoundry/ruby-buildpack,jumptvs/BP_Ruby,cloudfoundry/ruby-buildpack,Genius/heroku-buildpack-ruby,wakermahmud/heroku-buildpack-jekyll,cloudfoundry/ruby-buildpack,ablease/custom-buildpack,guidance-guarantee-programme/heroku-buildpack-princexml-old,hellojustin/heroku-buildpack-custom-ruby,instacart/heroku-buildpack-ruby,daltonrenaldo/heroku-buildpack-ruby,ascot21/heroku-buildpack-turbo-sprockets,amaltson/heroku-buildpack-ruby,DigitalInnovation/heroku-buildpack-mslabs,electricobjects/heroku-buildpack-ruby,vhx/heroku-buildpack,heroku/heroku-buildpack-ruby,space150/heroku-buildpack-ruby,DouglasAllen/heroku-buildpack-ruby,Altoros/ruby-buildpack,tenjikinc/heroku-buildpack-ruby,zoomer/heroku-buildpack-ruby-bower,dtao/deft-buildpack-ruby,gls1/heroku-buildpack-ruby-pdftk-new,mattmanning/heroku-buildpack-ruby-jekyll,schu/buildpack-testing,mperejda/heroku-buildpack-ruby,cloudfoundry/ruby-buildpack,DyegoCosta/heroku-buildpack-ruby,bellycard/heroku-buildpack-ruby,crdschurch/heroku-buildpack-ruby,aarongray/heroku-buildpack-ruby,qnyp/heroku-buildpack-ruby-bower,ChefSteps/heroku-buildpack-ruby,dtao/teeny-buildpack,teodor-pripoae/heroku-buildpack-ruby,moneyadviceservice/heroku-buildpack-ruby-bowndler,orenyk/heroku-buildpack-ruby,derrek/heroku-buildpack-ruby,CPPWind/ruby-buildpack,daltonrenaldo/heroku-buildpack-ruby,travis-ci/heroku-buildpack-ruby,adaptivelab/heroku-buildpack-adaptivelab-website-2,sky-uk/ruby-buildpack,brightbytes/heroku-buildpack-ruby-without-assets-precompile,ruby/heroku-buildpack-www-ruby-lang,KoanHealth/heroku-buildpack-marvin-setup,guidance-guarantee-programme/heroku-buildpack-princexml-old,cordata/heroku-buildpack-ruby,ericroberts/heroku-buildpack-ruby,dieze/heroku-buildpack-ruby-hooks,anay/buildpack-ruby-with-oracle-jdk,rowanoulton/heroku-buildpack-ruby,iamjarvo/ruby-buildpack,schu/buildpack-testing,iamjarvo/ruby-buildpack,ascot21/heroku-buildpack-turbo-sprockets,packetmonkey/heroku-buildpack-ruby,makifund/heroku-buildpack-ruby,DyegoCosta/heroku-buildpack-ruby,wakermahmud/heroku-buildpack-jekyll,donnykurnia/heroku-buildpack-ruby,cloudn/buildpack-ruby,Jonty/ruby-buildpack,sstelfox/buildpack-ruby,zidekmat/buildpack-ruby,0x00evil/heroku-buildpack-ruby,pkgr/buildpack-ruby-precise-old,jayshreeanand/heroku-buildpack-ruby,takii/heroku-buildpack-ruby,CPPWind/ruby-buildpack,tdenovan/heroku-buildpack-ruby,fgbreel/heroku-buildpack-ruby,ndbroadbent/heroku-buildpack-turbo-sprockets,adaptivelab/heroku-buildpack-adaptivelab-website-2,beydogan/ruby-buildpack,stefansundin/heroku-buildpack-ruby,hpcloud/ruby-buildpack,bellycard/heroku-buildpack-ruby,markaschneider/heroku-buildpack-ruby-ffmpeg-sox,cloudn/buildpack-ruby,jonseaberg/heroku-buildpack-turbo-sprockets,takii/db2rubybuildpack,michaelphines/alexa-nest,jumptvs/BP_Ruby,ekaranto/rails4-bluemix-buildpack,hpcloud/ruby-buildpack,gbenedict/heroku-buildpack-ruby,Scalingo/ruby-buildpack,vhx/heroku-buildpack,cloudfoundry/ruby-buildpack,sky-uk/help-heroku-buildpack,musicglue/heroku-buildpack-ruby,pkgr/buildpack-ruby-precise-old,rvizza/heroku-buildpack-gsl-ruby,codykrieger/heroku-buildpack-jekyll,AdStage/heroku-buildpack-ruby,bwaite-jaroop/heroku-buildpack-ruby,engineyard/heroku-buildpack-ruby,phusion/heroku-buildpack-ruby,centresource/heroku-buildpack-turbo-sprockets-pmp-ffm,sanemat/heroku-buildpack-ruby-tachikoma,fgbreel/heroku-buildpack-ruby,brightbytes/heroku-buildpack-ruby-without-assets-precompile,hixi/heroku-buildpack-ruby,scotta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