[NTG-context] \setupgraphics[location=local] does not work

How do I disable \externalfigure to search in texmf-directory? Using \setupexternalfigures [location=local] \starttext \externalfigure[cow] \stoptext still includes the figure. The tracker shows: graphics > inclusion > locations: local graphics > inclusion > path list: . .. ../.. graphics > inclusion > strategy: unknown format, prefer quality graphics > inclusion > found: ./cow.pdf -> /opt/context-minimals/texmf-context/tex/context/sample/cow.pdf Also, if location={local,global}, which directories of TEXMF tree are searched? Thanks, Aditya