On the graph for jsbench (browser WebKitGTK+ MiniBrowser) https://browserperfdash.igalia.com/dash/graph/
The test version when hovering over a point appears as tar.gz. It should be instead jsbench-2013.1.tar.gz
You can use python's os.path.basename function to get this:
In [1]: import os
In [2]: version_full="http://plg.uwaterloo.ca/~dynjs/jsbench/suite/jsbench-2013.1.tar.gz"
In [3]: os.path.basename(version_full)
Out[3]: 'jsbench-2013.1.tar.gz'