Text on path glyph rendering

Dear All,

when rendering a single middle aligned character on path with startOffset=0%
it may not render if the center of the glyph (= font design) is shifted
slightly to the left. In this case the final path position is negative hence
the related path coordinates cannot be found and that character is
suppressed.

This logic can be found in
org.apache.batik.bridge.GlyphLayout.doPathLayout()

I am not sure if this is the correct behaviour as same case is rendered
correctly in all major browsers. I'd rather expect retrieving the
coordinates for the startOffset without glyph position correction and
applying that shift after rotating and placing the text box along the path.

It can be tested with this example:

<svg xmlns="http://www.w3.org/2000/svg" 
   xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1"
   width="100%" height="100%" viewBox="0 0 600 600">
   <g transform="translate(300, 300)">
      <path id="textPath" d="M0 0 h100" stroke="red"/>
      <text><textPath xlink:href="#textPath" startOffset="0.0%" 
      text-anchor="middle" font-size="60px">8</textPath></text>
   </g>
</svg>

SVG 1.1 spec is IMHO vague at this point.
https://www.w3.org/TR/SVG/text.html#TextPathElement

Is the current behaviour bug or feature?

Thanks,

Jan