Various outlets, along with Apple, are assuring OS X users that they are not at particular risk from the Shellshock bash exploit. However, I use Python frequently on my system and wonder if that would increase my risk; and whether there is anything I can do to mitigate it (short of installing a different bash). 

I use Apple's (2.7.5) Python and bash, on OS X 10.9.5.
Using python does not increase your risk of being exposed to shellshock.
The best way to protect your computer is to make sure your computer has up-to-date patches and updates installed. 
Microsoft, Apple and various Linux distributions have all released updtes/patches which are supposed to fix the problem.
Does using Python on OS X expose me to Shellshock?