Do not mark backend as dead on error 500
Do not mark backend as dead on error 500

mfilotto/hipache,jamesbond12/hipache,appleboy/hipache,hackable/hipache,hackable/hipache,mfilotto/hipache,SensePlatform/hipache,rutsky/hipache-1,kalabox/hipache,crowdworks/lopache,jamesbond12/hipache,appleboy/hipache,rutsky/hipache-1,aldryncore/hipache,mfilotto/hipache,jamesbond12/hipache,appleboy/hipache,kalabox/hipache,yonglehou/hipache,kalabox/hipache,biddyweb/hipache,rutsky/hipache-1,biddyweb/hipache,jkingyens/hipache,jamesbond12/hipache,kotnik/hipache,yonglehou/hipache,jkingyens/hipache,aldryncore/hipache,crowdworks/lopache,sahilsk/tb_hipache,crowdworks/lopache,kalabox/hipache,SensePlatform/hipache,yonglehou/hipache,aldryncore/hipache,aldryncore/hipache,kotnik/hipache,SensePlatform/hipache,rutsky/hipache-1,jkingyens/hipache,sahilsk/tb_hipache,sahilsk/tb_hipache,mfilotto/hipache,hackable/hipache,hackable/hipache,crowdworks/lopache,yonglehou/hipache,biddyweb/hipache,SensePlatform/hipache,biddyweb/hipache