Comment 2 for bug 223986

The path has a Live Path Effect (LPE) applied, as can be seen in the LPE dialog (ctrl+shift+7). The LPE takes the inkscape:original-d information, performs a calculation, then outputs the result in the 'd' attribute.
Inkscape ignores setting the 'd' attribute because it is generated by Inkscape and the user should indeed edit 'original-d' instead.