MAINT: In _create_generator only overwrite perf_tracker when it's None.
MAINT: In _create_generator only overwrite perf_tracker when it's None.

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