Fixed test suite bisection on Python 3.

#!/usr/bin/env python

from __future__ import division

import logging

import os

import shutil

    iteration = 1

    while len(test_labels) > 1:

        midpoint = len(test_labels)/2

        midpoint = len(test_labels) // 2

        test_labels_a = test_labels[:midpoint] + [bisection_label]

        test_labels_b = test_labels[midpoint:] + [bisection_label]

        print('***** Pass %da: Running the first half of the test suite' % iteration)