Pythonic quicksort algorithm
Looks good in general. Few comments.


Missing import random.
Random pivot selection is just one of many possible strategies. It may or may not be a good strategy depending on the nature of data. Only the client knows what a suitable strategy will be; let him chose.
No Raw Loops mantra: Every loop possible represents an algorithm, often very important itself. In this case the algorithm is partition. It is worthy to be factored out in a function of its own.