Deriving ubuntu from debian instead of linux.
Deriving ubuntu from debian instead of linux.

Fixes #6756

SGuyGe/corefx,parjong/corefx,alexperovich/corefx,krk/corefx,shahid-pk/corefx,JosephTremoulet/corefx,mmitche/corefx,Jiayili1/corefx,DnlHarvey/corefx,JosephTremoulet/corefx,jhendrixMSFT/corefx,iamjasonp/corefx,mazong1123/corefx,lggomez/corefx,YoupHulsebos/corefx,nchikanov/corefx,rahku/corefx,twsouthwick/corefx,nchikanov/corefx,ravimeda/corefx,rjxby/corefx,stone-li/corefx,weltkante/corefx,tijoytom/corefx,ericstj/corefx,JosephTremoulet/corefx,dotnet-bot/corefx,nbarbettini/corefx,nbarbettini/corefx,Petermarcu/corefx,yizhang82/corefx,shmao/corefx,Petermarcu/corefx,krytarowski/corefx,seanshpark/corefx,JosephTremoulet/corefx,tstringer/corefx,yizhang82/corefx,rjxby/corefx,weltkante/corefx,stephenmichaelf/corefx,Jiayili1/corefx,khdang/corefx,tstringer/corefx,cydhaselton/corefx,MaggieTsang/corefx,tijoytom/corefx,Jiayili1/corefx,alphonsekurian/corefx,yizhang82/corefx,krytarowski/corefx,Jiayili1/corefx,jhendrixMSFT/corefx,axelheer/corefx,jlin177/corefx,jlin177/corefx,the-dwyer/corefx,dhoehna/corefx,alexperovich/corefx,iamjasonp/corefx,ellismg/corefx,the-dwyer/corefx,YoupHulsebos/corefx,shahid-pk/corefx,mazong1123/corefx,iamjasonp/corefx,seanshpark/corefx,lggomez/corefx,krytarowski/corefx,seanshpark/corefx,seanshpark/corefx,the-dwyer/corefx,weltkante/corefx,DnlHarvey/corefx,shimingsg/corefx,cydhaselton/corefx,mmitche/corefx,krytarowski/corefx,ellismg/corefx,shmao/corefx,fgreinacher/corefx,cydhaselton/corefx,stone-li/corefx,lggomez/corefx,ericstj/corefx,manu-silicon/corefx,pallavit/corefx,mazong1123/corefx,BrennanConroy/corefx,marksmeltzer/corefx,tstringer/corefx,iamjasonp/corefx,zhenlan/corefx,Priya91/corefx-1,fgreinacher/corefx,parjong/corefx,mazong1123/corefx,khdang/corefx,wtgodbe/corefx,krk/corefx,BrennanConroy/corefx,Priya91/corefx-1,rjxby/corefx,jcme/corefx,JosephTremoulet/corefx,Petermarcu/corefx,dsplaisted/corefx,mmitche/corefx,alphonsekurian/corefx,pallavit/corefx,cartermp/corefx,rubo/corefx,rubo/corefx,billwert/corefx,MaggieTsang/corefx,SGuyGe/corefx,shahid-pk/corefx,stephenmichaelf/corefx,shmao/corefx,ravimeda/corefx,weltkante/corefx,ptoonen/corefx,alexperovich/corefx,manu-silicon/corefx,elijah6/corefx,cartermp/corefx,cartermp/corefx,YoupHulsebos/corefx,twsouthwick/corefx,yizhang82/corefx,ViktorHofer/corefx,stephenmichaelf/corefx,rjxby/corefx,SGuyGe/corefx,alphonsekurian/corefx,stone-li/corefx,ellismg/corefx,the-dwyer/corefx,fgreinacher/corefx,nbarbettini/corefx,alphonsekurian/corefx,cartermp/corefx,Petermarcu/corefx,jhendrixMSFT/corefx,krk/corefx,dotnet-bot/corefx,axelheer/corefx,shimingsg/corefx,Ermiar/corefx,gkhanna79/corefx,richlander/corefx,ravimeda/corefx,Petermarcu/corefx,elijah6/corefx,dsplaisted/corefx,rahku/corefx,Jiayili1/corefx,billwert/corefx,nbarbettini/corefx,DnlHarvey/corefx,dhoehna/corefx,DnlHarvey/corefx,pallavit/corefx,ellismg/corefx,nbarbettini/corefx,rjxby/corefx,nchikanov/corefx,fgreinacher/corefx,Ermiar/corefx,stone-li/corefx,parjong/corefx,wtgodbe/corefx,lggomez/corefx,YoupHulsebos/corefx,shimingsg/corefx,yizhang82/corefx,jcme/corefx,ptoonen/corefx,kkurni/corefx,shmao/corefx,Ermiar/corefx,ericstj/corefx,dsplaisted/corefx,billwert/corefx,billwert/corefx,DnlHarvey/corefx,richlander/corefx,gkhanna79/corefx,billwert/corefx,shimingsg/corefx,alphonsekurian/corefx,marksmeltzer/corefx,khdang/corefx,adamralph/corefx,mazong1123/corefx,shimingsg/corefx,krk/corefx,richlander/corefx,cydhaselton/corefx,parjong/corefx,zhenlan/corefx,lggomez/corefx,nbarbettini/corefx,DnlHarvey/corefx,axelheer/corefx,Ermiar/corefx,shimingsg/corefx,pallavit/corefx,MaggieTsang/corefx,ptoonen/corefx,jcme/corefx,Priya91/corefx-1,mmitche/corefx,elijah6/corefx,nbarbettini/corefx,stephenmichaelf/corefx,twsouthwick/corefx,nchikanov/corefx,mmitche/corefx,nchikanov/corefx,kkurni/corefx,DnlHarvey/corefx,nchikanov/corefx,Chrisboh/corefx,wtgodbe/corefx,ViktorHofer/corefx,elijah6/corefx,alphonsekurian/corefx,pallavit/corefx,ericstj/corefx,gkhanna79/corefx,Priya91/corefx-1,manu-silicon/corefx,shahid-pk/corefx,pallavit/corefx,manu-silicon/corefx,YoupHulsebos/corefx,YoupHulsebos/corefx,jhendrixMSFT/corefx,dhoehna/corefx,parjong/corefx,rubo/corefx,dotnet-bot/corefx,Chrisboh/corefx,kkurni/corefx,marksmeltzer/corefx,twsouthwick/corefx,rahku/corefx,shimingsg/corefx,parjong/corefx,tijoytom/corefx,Priya91/corefx-1,adamralph/corefx,alexperovich/corefx,alphonsekurian/corefx,seanshpark/corefx,gkhanna79/corefx,lggomez/corefx,Chrisboh/corefx,shmao/corefx,ptoonen/corefx,manu-silicon/corefx,iamjasonp/corefx,dhoehna/corefx,MaggieTsang/corefx,dhoehna/corefx,rubo/corefx,cydhaselton/corefx,krk/corefx,dotnet-bot/corefx,stephenmichaelf/corefx,krytarowski/corefx,ViktorHofer/corefx,zhenlan/corefx,tijoytom/corefx,zhenlan/corefx,Petermarcu/corefx,stone-li/corefx,tstringer/corefx,cydhaselton/corefx,tijoytom/corefx,manu-silicon/corefx,shahid-pk/corefx,yizhang82/corefx,ravimeda/corefx,wtgodbe/corefx,richlander/corefx,cydhaselton/corefx,ViktorHofer/corefx,Ermiar/corefx,billwert/corefx,richlander/corefx,Jiayili1/corefx,iamjasonp/corefx,jlin177/corefx,weltkante/corefx,mmitche/corefx,Ermiar/corefx,wtgodbe/corefx,BrennanConroy/corefx,stone-li/corefx,ellismg/corefx,Chrisboh/corefx,richlander/corefx,stone-li/corefx,nchikanov/corefx,dotnet-bot/corefx,stephenmichaelf/corefx,Priya91/corefx-1,dhoehna/corefx,mmitche/corefx,rjxby/corefx,jhendrixMSFT/corefx,YoupHulsebos/corefx,kkurni/corefx,wtgodbe/corefx,Jiayili1/corefx,manu-silicon/corefx,jcme/corefx,krk/corefx,zhenlan/corefx,weltkante/corefx,ptoonen/corefx,jcme/corefx,axelheer/corefx,seanshpark/corefx,axelheer/corefx,MaggieTsang/corefx,dotnet-bot/corefx,parjong/corefx,SGuyGe/corefx,rahku/corefx,MaggieTsang/corefx,gkhanna79/corefx,twsouthwick/corefx,kkurni/corefx,JosephTremoulet/corefx,jhendrixMSFT/corefx,twsouthwick/corefx,ericstj/corefx,elijah6/corefx,tstringer/corefx,the-dwyer/corefx,Ermiar/corefx,gkhanna79/corefx,weltkante/corefx,krytarowski/corefx,tijoytom/corefx,JosephTremoulet/corefx,jlin177/corefx,jlin177/corefx,elijah6/corefx,rahku/corefx,krk/corefx,elijah6/corefx,ptoonen/corefx,jhendrixMSFT/corefx,stephenmichaelf/corefx,SGuyGe/corefx,rahku/corefx,krytarowski/corefx,rahku/corefx,adamralph/corefx,alexperovich/corefx,alexperovich/corefx,yizhang82/corefx,Chrisboh/corefx,ellismg/corefx,lggomez/corefx,dhoehna/corefx,seanshpark/corefx,khdang/corefx,mazong1123/corefx,ravimeda/corefx,billwert/corefx,tstringer/corefx,richlander/corefx,ViktorHofer/corefx,khdang/corefx,shahid-pk/corefx,ViktorHofer/corefx,rubo/corefx,tijoytom/corefx,ravimeda/corefx,alexperovich/corefx,SGuyGe/corefx,ericstj/corefx,jlin177/corefx,iamjasonp/corefx,ptoonen/corefx,khdang/corefx,jcme/corefx,Chrisboh/corefx,shmao/corefx,cartermp/corefx,rjxby/corefx,shmao/corefx,twsouthwick/corefx,gkhanna79/corefx,the-dwyer/corefx,ericstj/corefx,MaggieTsang/corefx,the-dwyer/corefx,marksmeltzer/corefx,marksmeltzer/corefx,kkurni/corefx,marksmeltzer/corefx,zhenlan/corefx,Petermarcu/corefx,jlin177/corefx,cartermp/corefx,ravimeda/corefx,zhenlan/corefx,axelheer/corefx,marksmeltzer/corefx,wtgodbe/corefx,dotnet-bot/corefx,mazong1123/corefx,ViktorHofer/corefx