fix traceback on /credits (bug 853695)
fix traceback on /credits (bug 853695)

tsl143/zamboni,koehlermichael/olympia,aviarypl/mozilla-l10n-addons-server,kumar303/olympia,andymckay/addons-server,shahbaz17/zamboni,ayushagrawal288/zamboni,diox/zamboni,mozilla/addons-server,mdaif/olympia,Nolski/olympia,magopian/olympia,kmaglione/olympia,diox/olympia,diox/olympia,harikishen/addons-server,Witia1/olympia,mstriemer/olympia,wagnerand/addons-server,anaran/olympia,diox/olympia,ingenioustechie/zamboni,Joergen/olympia,andymckay/olympia,kmaglione/olympia,diox/olympia,andymckay/olympia,jpetto/olympia,kumar303/olympia,magopian/olympia,Prashant-Surya/addons-server,koehlermichael/olympia,ayushagrawal288/zamboni,atiqueahmedziad/addons-server,aviarypl/mozilla-l10n-addons-server,yfdyh000/olympia,crdoconnor/olympia,muffinresearch/olympia,muffinresearch/olympia,diox/zamboni,ingenioustechie/zamboni,Prashant-Surya/addons-server,mozilla/olympia,ngokevin/zamboni,spasovski/zamboni,anaran/olympia,tsl143/zamboni,kumar303/zamboni,johancz/olympia,wagnerand/addons-server,johancz/olympia,harry-7/addons-server,johancz/olympia,shahbaz17/zamboni,washort/zamboni,bqbn/addons-server,Jobava/zamboni,robhudson/zamboni,mdaif/olympia,bqbn/addons-server,tsl143/addons-server,kumar303/zamboni,mstriemer/olympia,mdaif/olympia,kumar303/olympia,psiinon/addons-server,aviarypl/mozilla-l10n-addons-server,mozilla/zamboni,mozilla/zamboni,SuriyaaKudoIsc/olympia,andymckay/zamboni,andymckay/addons-server,luckylavish/zamboni,luckylavish/zamboni,anaran/olympia,wagnerand/addons-server,mdaif/olympia,luckylavish/zamboni,eviljeff/zamboni,mrrrgn/olympia,muffinresearch/olympia,Joergen/zamboni,beni55/olympia,washort/zamboni,magopian/olympia,mrrrgn/olympia,muffinresearch/addons-server,kumar303/zamboni,lavish205/olympia,eviljeff/olympia,jasonthomas/zamboni,jpetto/olympia,Joergen/olympia,mudithkr/zamboni,Jobava/zamboni,Joergen/zamboni,kmaglione/olympia,SuriyaaKudoIsc/olympia,Revanth47/addons-server,spasovski/zamboni,mozilla/addons-server,mstriemer/olympia,tsl143/addons-server,magopian/olympia,Nolski/olympia,koehlermichael/olympia,andymckay/addons-server,tsl143/zamboni,yfdyh000/olympia,mdaif/olympia,wagnerand/zamboni,jasonthomas/zamboni,mozilla/olympia,robhudson/zamboni,diox/zamboni,tsl143/addons-server,kumar303/addons-server,bqbn/addons-server,eviljeff/olympia,mudithkr/zamboni,lavish205/olympia,elysium001/zamboni,jpetto/olympia,yfdyh000/olympia,mudithkr/zamboni,beni55/olympia,eviljeff/olympia,mozilla/addons-server,kmaglione/olympia,ddurst/zamboni,mrrrgn/olympia,Hitechverma/zamboni,Witia1/olympia,diox/zamboni,ngokevin/zamboni,crdoconnor/olympia,jasonthomas/zamboni,eviljeff/olympia,mrrrgn/olympia,wagnerand/zamboni,atiqueahmedziad/addons-server,spasovski/zamboni,mstriemer/addons-server,Jobava/zamboni,clouserw/zamboni,crdoconnor/olympia,atiqueahmedziad/addons-server,koehlermichael/olympia,andymckay/olympia,Hitechverma/zamboni,mrrrgn/olympia,Witia1/olympia,Jobava/zamboni,robhudson/zamboni,clouserw/zamboni,wagnerand/olympia,bqbn/addons-server,ingenioustechie/zamboni,ddurst/zamboni,ngokevin/zamboni,jamesthechamp/zamboni,shahbaz17/zamboni,Prashant-Surya/addons-server,mozilla/olympia,jamesthechamp/zamboni,washort/zamboni,shahbaz17/zamboni,spasovski/zamboni,crdoconnor/olympia,magopian/olympia,muffinresearch/addons-server,jasonthomas/zamboni,aviarypl/mozilla-l10n-addons-server,mozilla/zamboni,tsl143/zamboni,Joergen/zamboni,Hitechverma/zamboni,Joergen/olympia,ayushagrawal288/zamboni,psiinon/addons-server,jpetto/olympia,wagnerand/zamboni,mstriemer/zamboni,SuriyaaKudoIsc/olympia,harikishen/addons-server,jamesthechamp/zamboni,Joergen/olympia,muffinresearch/addons-server,Joergen/zamboni,lavish205/olympia,SuriyaaKudoIsc/olympia,clouserw/zamboni,harry-7/addons-server,johancz/olympia,yfdyh000/olympia,ayushagrawal288/zamboni,Hitechverma/zamboni,crdoconnor/olympia,Joergen/zamboni,andymckay/zamboni,ddurst/zamboni,luckylavish/zamboni,lavish205/olympia,mstriemer/olympia,wagnerand/olympia,kumar303/addons-server,Prashant-Surya/addons-server,atiqueahmedziad/addons-server,wagnerand/zamboni,Revanth47/addons-server,kumar303/zamboni,mstriemer/zamboni,harry-7/addons-server,psiinon/addons-server,mstriemer/zamboni,yfdyh000/olympia,beni55/olympia,elysium001/zamboni,harry-7/addons-server,eviljeff/zamboni,kumar303/addons-server,Revanth47/addons-server,mstriemer/addons-server,mudithkr/zamboni,Nolski/olympia,johancz/olympia,elysium001/zamboni,kumar303/olympia,beni55/olympia,wagnerand/addons-server,Nolski/olympia,anaran/olympia,ingenioustechie/zamboni,clouserw/zamboni,mozilla/olympia,Nolski/olympia,mozilla/zamboni,andymckay/zamboni,elysium001/zamboni,mstriemer/addons-server,eviljeff/zamboni,jamesthechamp/zamboni,koehlermichael/olympia,muffinresearch/olympia,washort/zamboni,muffinresearch/olympia,kmaglione/olympia,kumar303/addons-server,harikishen/addons-server,robhudson/zamboni,mozilla/addons-server,Joergen/olympia,wagnerand/olympia,ddurst/zamboni,psiinon/addons-server,Revanth47/addons-server,mstriemer/zamboni,andymckay/olympia,wagnerand/olympia,muffinresearch/addons-server,Joergen/zamboni,beni55/olympia,mstriemer/addons-server,muffinresearch/addons-server,andymckay/addons-server,harikishen/addons-server,Witia1/olympia,eviljeff/zamboni,tsl143/addons-server,Witia1/olympia