Comment 1 for bug 1248104

    confirmed on Windows XP, Inkscape rev 12755.
    strictly speaking, this is illegal svg code, not because the radius is zero, but because the start point and endpoint of the arc are the same. In this case the arc is indeterminate, cannot be specified uniquely. The svg spec indicates that nothing should be drawn in this case. fwiw Internet Explorer 8 (Adobe SVG viewer) shows exactly the same deficiency when displaying the original svg file, as does the dxf output.
    in any event, this should be fixable, I'll look into it ...