BUG: Only localize benchmark index if it is naive.
BUG: Only localize benchmark index if it is naive.

Check for whether or not the index's timezone is UTC or not before
attempting to localize, since an already localized index throws an
error when tz_localize is called.

nborggren/zipline,DVegaCapital/zipline,otmaneJai/Zipline,keir-rex/zipline,ronalcc/zipline,gwulfs/zipline,ChinaQuants/zipline,CDSFinance/zipline,Scapogo/zipline,enigmampc/catalyst,kmather73/zipline,dkushner/zipline,StratsOn/zipline,MonoCloud/zipline,AlirezaShahabi/zipline,CDSFinance/zipline,Scapogo/zipline,kmather73/zipline,bartosh/zipline,wubr2000/zipline,semio/zipline,AlirezaShahabi/zipline,iamkingmaker/zipline,cmorgan/zipline,nborggren/zipline,aajtodd/zipline,morrisonwudi/zipline,MonoCloud/zipline,grundgruen/zipline,erikness/AlephOne,joequant/zipline,michaeljohnbennett/zipline,davidastephens/zipline,davidastephens/zipline,DVegaCapital/zipline,jordancheah/zipline,bartosh/zipline,CarterBain/AlephNull,stkubr/zipline,wilsonkichoi/zipline,grundgruen/zipline,quantopian/zipline,wubr2000/zipline,dkushner/zipline,humdings/zipline,humdings/zipline,gwulfs/zipline,umuzungu/zipline,morrisonwudi/zipline,jordancheah/zipline,dhruvparamhans/zipline,StratsOn/zipline,dmitriz/zipline,stkubr/zipline,keir-rex/zipline,umuzungu/zipline,sketchytechky/zipline,wilsonkichoi/zipline,dmitriz/zipline,enigmampc/catalyst,alphaBenj/zipline,zhoulingjun/zipline,michaeljohnbennett/zipline,CarterBain/AlephNull,chrjxj/zipline,iamkingmaker/zipline,otmaneJai/Zipline,mattcaldwell/zipline,magne-max/zipline-ja,erikness/AlephOne,sketchytechky/zipline,ronalcc/zipline,euri10/zipline,dhruvparamhans/zipline,mattcaldwell/zipline,alphaBenj/zipline,euri10/zipline,aajtodd/zipline,quantopian/zipline,joequant/zipline,chrjxj/zipline,semio/zipline,cmorgan/zipline,YuepengGuo/zipline,florentchandelier/zipline,magne-max/zipline-ja,ChinaQuants/zipline,florentchandelier/zipline,jimgoo/zipline-fork,jimgoo/zipline-fork,zhoulingjun/zipline,YuepengGuo/zipline