[NTG-context] metafun paralleled does not give a parallel path

The following used to produce three parallel lines. Now it produces one straight line and two arcs. \starttext \startMPcode z0 = origin; z1 = 72dir(45); dotlabel.bot("z0", z0); draw z0--z1; draw (z0--z1) paralleled -15 withcolor red; draw (z0--z1) paralleled 15 withcolor blue; \stopMPcode \stoptext