fix STACK_DIR variable
fix STACK_DIR variable

liuquansheng47/devstack,vishnugonela/devstack,r-mibu/devstack,CloudServer/devstack,noironetworks/devstack,nttmcl/devstack_public,BSJAIN92/OpenStack,LoHChina/devstack,nuxeh/devstack,savi-dev/devstack,olivierlemasle/devstack,promptworks/devstack,kplus/devstack-moonshot,HPCHub/devstack,eshnil2000/devstack,tianweizhang/devstack,varunarya10/devstack,herrsechs/devstack,samgoon/devstack,ozamiatin/devstack,pacinete/devstack,NaokiMiyata/devstack,deepakselvaraj/devstack,bljgaurav/openstack-test,sequenceiq/devstack,bigswitch/devstack,atulpatil301/devstack,bswartz/devstack,upadhyay-prashant/devstack,BSJAIN92/OpenStack,openstack-dev/devstack,parul24/devstack,Mahito/devstack,mc2014/devstack,williamthegrey/devstack,pombredanne/devstack,nati/devstack_public,sc68cal/devstack,pczerkas/devstack,dirkmueller/devstack,Yuriy-Leonov/devstack,atulpatil301/devstack,LoHChina/devstack,cloudbuilders/devstack,srics/devstack,prithivm/branch01,mmasaki/devstack,NaokiMiyata/devstack,mssumanth/devstack,sc68cal/devstack,Mahito/devstack,affo/devstack,pacinete/devstack,ewindisch/raspi-devstack,citrix-openstack-build/devstack,bswartz/devstack,liuquansheng47/devstack,dtroyer/devstack,Millnert/contrail-devstack,promptworks/devstack,j4/devstack,vsham20/devstack,rushiagr/devstack,Juniper/devstack,olivierlemasle/devstack,yamt/devstack,CiscoSystems/devstack,savi-dev/devstack,ykaneko/devstack,vsham20/devstack,mssumanth/devstack,virtualopensystems/devstack,flavio-fernandes/devstack,bq-xiao/devstack,andrewrothstein/devstack,affo/devstack,cloudbuilders/devstack,JioCloud/devstack,HPCHub/devstack,pombredanne/devstack,pczerkas/devstack,dtroyer/devstack,eharney/devstack,TwinkleChawla/devstack,nawawi/openstack,dirkmueller/devstack,vishnugonela/devstack,wenhuizhang/devstack,r-mibu/devstack,andrewrothstein/devstack,armando-migliaccio/devstack,thomasem/devstack,TwinkleChawla/devstack,wenhuizhang/devstack,richliu/devstack,varunarya10/devstack,group-policy/devstack,bljgaurav/openstack-test,group-policy/devstack,openstack-dev/devstack,ykaneko/devstack,nttmcl/devstack_public,jamielennox/devstack,sequenceiq/devstack,flavio-fernandes/devstack,sstrato/devstack,kplus/devstack-moonshot,eharney/devstack,ewindisch/raspi-devstack,nawawi/openstack,samgoon/devstack,ozamiatin/devstack,inkerra/devstack,prithivm/branch01,costingalan/devstack,noironetworks/devstack,thomasem/devstack,rushiagr/devstack,neerja28/Devstack_GlusterFS,neerja28/Devstack_GlusterFS,bq-xiao/devstack,innodee/openstackk,herrsechs/devstack,nuxeh/devstack,mc2014/devstack,CloudServer/devstack,mmasaki/devstack,nati/devstack_public,bigswitch/devstack,parul24/devstack,shootstar/devstacktest,upadhyay-prashant/devstack,avvocatodemarchis/devstack,j4/devstack,tianweizhang/devstack,avvocatodemarchis/devstack,richliu/devstack,citrix-openstack-build/devstack,costingalan/devstack