Setting LOGFILE to a file in root directory wipes everything
Setting LOGFILE to a file in root directory wipes everything

clean.sh picks the parent of LOGFILE and wipes it clean! So if you
set it to a log file in the users root directory, you lose everything

We should delete just the LOGFILE and cleanup LOGDIR and SCREEN_LOGDIR if
they are explicitly set.

Change-Id: I45745427dcaed3dcf0b78cc9ed680833d9d555e8

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