Broken support for closed arc shape with two radii

[TrevorPage]

In Inkscape, a semi-circle arc can be made either open or closed. If it's made closed then there are two radii added to make it a fully-enclosed shape.

When attempting to render a closed arc with the two radii, one radial is missing. This is suspected to be due to broken support of the 'z' command possibly, so the path is not completed properly.

A second issue is that I did this using a very thick path, and the arc and radial don't look nicely joined which suggests I need to properly sort out path miter.

Path that shows the issues:

<path
   transform="matrix(1.6694954,0,0,1.6694954,-490.42618,100.25687)"
   sodipodi:type="arc"
   style="fill:none;stroke:#38a3a6;stroke-width:30;stroke-miterlimit:4;stroke-opacity:1;stroke-dasharray:none"
   id="path2987-1-1-4"
   sodipodi:cx="350"
   sodipodi:cy="512.36218"
   sodipodi:rx="160"
   sodipodi:ry="160"
   d="m 484.18729,425.21994 a 160,160 0 0 1 25.20386,73.19732 L 350,512.36218 z"
   sodipodi:start="5.7072267"
   sodipodi:end="6.1959188" />