Fix TRACKING_DEPENDS mode
Fix TRACKING_DEPENDS mode

TRACKING_DEPENDS mode was added in I89677fd54635e82b10ab674ddeb9ffb3f1a755f0

TRACKING_DEPENDS creates a global virtualenv and assumes it exists for
all pip_installs (except for installing virtualenv), so we need to set
this up before any other pip install

Change-Id: Iebe6295913094b32124295e7c5e674e1cebaaa87

j4/devstack,olivierlemasle/devstack,LoHChina/devstack,NaokiMiyata/devstack,Mahito/devstack,bq-xiao/devstack,sc68cal/devstack,kplus/devstack-moonshot,group-policy/devstack,mc2014/devstack,affo/devstack,andrewrothstein/devstack,neerja28/Devstack_GlusterFS,sequenceiq/devstack,bswartz/devstack,andrewrothstein/devstack,avvocatodemarchis/devstack,parul24/devstack,nawawi/openstack,eharney/devstack,HPCHub/devstack,noironetworks/devstack,pombredanne/devstack,richliu/devstack,openstack-dev/devstack,rushiagr/devstack,bigswitch/devstack,affo/devstack,mmasaki/devstack,prithivm/branch01,richliu/devstack,promptworks/devstack,kplus/devstack-moonshot,pacinete/devstack,openstack-dev/devstack,TwinkleChawla/devstack,thomasem/devstack,bq-xiao/devstack,varunarya10/devstack,atulpatil301/devstack,j4/devstack,mmasaki/devstack,pczerkas/devstack,upadhyay-prashant/devstack,nawawi/openstack,eharney/devstack,nuxeh/devstack,samgoon/devstack,nuxeh/devstack,sc68cal/devstack,bljgaurav/openstack-test,TwinkleChawla/devstack,vsham20/devstack,wenhuizhang/devstack,mssumanth/devstack,vishnugonela/devstack,neerja28/Devstack_GlusterFS,vishnugonela/devstack,Mahito/devstack,varunarya10/devstack,vsham20/devstack,dirkmueller/devstack,dirkmueller/devstack,flavio-fernandes/devstack,promptworks/devstack,noironetworks/devstack,dtroyer/devstack,parul24/devstack,herrsechs/devstack,liuquansheng47/devstack,wenhuizhang/devstack,group-policy/devstack,NaokiMiyata/devstack,bswartz/devstack,CloudServer/devstack,prithivm/branch01,bigswitch/devstack,sequenceiq/devstack,ozamiatin/devstack,thomasem/devstack,avvocatodemarchis/devstack,pczerkas/devstack,pombredanne/devstack,flavio-fernandes/devstack,bljgaurav/openstack-test,costingalan/devstack,mssumanth/devstack,BSJAIN92/OpenStack,atulpatil301/devstack,HPCHub/devstack,dtroyer/devstack,mc2014/devstack,herrsechs/devstack,costingalan/devstack,upadhyay-prashant/devstack,CloudServer/devstack,ozamiatin/devstack,samgoon/devstack,rushiagr/devstack,liuquansheng47/devstack,LoHChina/devstack,olivierlemasle/devstack,pacinete/devstack,BSJAIN92/OpenStack