Don't depend on cx_Freeze for tests.

scripts/freeze.py

@@ -29,7 +29,8 @@ import os.path
 import sys
 import distutils
 
-import cx_Freeze as cx
+import cx_Freeze as cx  # pylint: disable=import-error
+# cx_Freeze is hard to install (needs C extensions) so we don't check for it.
 
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), os.pardir))
 from scripts import setupcommon

scripts/init_venv.py

@@ -71,7 +71,7 @@ def get_dev_packages(short=False):
         short: Remove the version specification.
     """
     packages = ['colorlog', 'flake8', 'astroid==1.2.1', 'pylint==1.3.1',
-                'pep257', 'colorama', 'beautifulsoup4', 'cx_Freeze']
+                'pep257', 'colorama', 'beautifulsoup4']
     if short:
         packages = [re.split(r'[<>=]', p)[0] for p in packages]
     return packages