TST Fixed existing tests on timeseries.aggregate_returns.
TST Fixed existing tests on timeseries.aggregate_returns.

dursk/pyfolio,raybuhr/pyfolio,femtotrader/pyfolio,YihaoLu/pyfolio,sketchytechky/pyfolio,r0k3/pyfolio,femtotrader/pyfolio,dursk/pyfolio,quantopian/pyfolio,raybuhr/pyfolio,sketchytechky/pyfolio,r0k3/pyfolio,ChinaQuants/pyfolio,ChinaQuants/pyfolio,YihaoLu/pyfolio,quantopian/pyfolio,yanheven/pyfolio,chayapan/pyfolio,yanheven/pyfolio