Fix util.which to deal with file names with path components
Fix util.which to deal with file names with path components

mdboom/asv,mdboom/asv,airspeed-velocity/asv,qwhelan/asv,pv/asv,airspeed-velocity/asv,spacetelescope/asv,qwhelan/asv,qwhelan/asv,spacetelescope/asv,pv/asv,pv/asv,pv/asv,spacetelescope/asv,airspeed-velocity/asv,mdboom/asv,qwhelan/asv,mdboom/asv,airspeed-velocity/asv,spacetelescope/asv