add test for matching existing src/currentSrc
add test for matching existing src/currentSrc

purposeindustries/picturefill,iancrowther/picturefill,chrismcandrew/picturefill,ddeveloperr/picturefill,scottjehl/picturefill,ddeveloperr/picturefill,nucliweb/picturefill,yufi113/picturefill,chrismcandrew/picturefill,samiadelgado/picturefill,patrickkettner/picturefill,albell/picturefill,guardian/picturefill,rockmandew/picturefill,yufi113/picturefill,yubin-huang/picturefill,demateu/picturefill,iancrowther/picturefill,samiadelgado/picturefill,mcanthony/picturefill,guardian/picturefill,scottjehl/picturefill,footiealf/picturefill,yubin-huang/picturefill,albell/picturefill,rockmandew/picturefill,purposeindustries/picturefill,patrickkettner/picturefill,demateu/picturefill,footiealf/picturefill,mcanthony/picturefill