From the devdocs:

1. http://matplotlib.org/devdocs/examples/lines_bars_and_markers/scatter_with_legend.html
   Compare the legend in the svg version to the png version. At least on my system (OSX, Firefox or Chrome), the circles in the svg legend appear to consist of a smaller disk inside a larger one.
2. The Imagemagick "convert" program can't handle our svg file.