Fixes bug in test where period_end is too early.
Fixes bug in test where period_end is too early.

Grabs period end before we remove trades.

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