pylint: Update pylint to 1.7.1, run on tests/ and tools and fix complaints.

The motivation for this is that
 a.) 1.7.1 runs with python 3.6 (bionic)
 b.) we want to run pylint on tests/ and tools for the same reasons
     that we want to run it on cloudinit/

The changes are described below.
- Update tox.ini to invoke pylint v1.7.1.
- Modify .pylintrc generated-members ignore mocked object members (m_.*)
- Replace "dangerous" params defaulting to {}
- Fix up cloud_tests use of platforms
- Cast some instance objects to with dict()
- Handle python2.7 vs 3+ ConfigParser use of readfp (deprecated)
- Update use of assertEqual(<boolean>, value) to assert<Boolean>(value)
- replace depricated assertRegexp -> assertRegex
- Remove useless test-class calls to super class
- Assign class property accessors a result and use it
- Fix missing class member in CepkoResultTests
- Fix Cheetah test import

1 files changed, 3 insertions, 1 deletions

diff --git a/tests/cloud_tests/config.py b/tests/cloud_tests/config.py
index 52fc2bda..8bd569fd 100644
--- a/tests/cloud_tests/config.py
+++ b/tests/cloud_tests/config.py
@@ -92,7 +92,7 @@ def load_platform_config(platform_name, require_enabled=False):
 
 
 def load_os_config(platform_name, os_name, require_enabled=False,
-                   feature_overrides={}):
+                   feature_overrides=None):
     """Load configuration for os.
 
     @param platform_name: platform name to load os config for
@@ -101,6 +101,8 @@ def load_os_config(platform_name, os_name, require_enabled=False,
     @param feature_overrides: feature flag overrides to merge with features
     @return_value: config dict
     """
+    if feature_overrides is None:
+        feature_overrides = {}
     main_conf = c_util.read_conf(RELEASES_CONF)
     default = main_conf['default_release_config']
     image = main_conf['releases'][os_name]