The librsvg version used on Wikimedia's servers seems to be pretty outdated.
version used is
pre-Cairo. The first stable librsvg version using Cairo backend was released
2005-09-15 and it works just fine.
The outdated version holds back some SVGs that could replace current PNGs.
Problems include lacking support for dashed lines, lack of support for viewboxes
and some various rendering anomalities. Here are some examples: