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, 2 insertions, 1 deletions

diff --git a/tests/unittests/test_datasource/test_ec2.py b/tests/unittests/test_datasource/test_ec2.py
index ba042eac..f0dc8338 100644
--- a/tests/unittests/test_datasource/test_ec2.py
+++ b/tests/unittests/test_datasource/test_ec2.py
@@ -330,7 +330,8 @@ class TestEc2(test_helpers.HttprettyTestCase):
         ds.fallback_nic = 'eth9'
         with mock.patch(get_interface_mac_path) as m_get_interface_mac:
             m_get_interface_mac.return_value = mac1
-            ds.network_config  # Will re-crawl network metadata
+            nc = ds.network_config  # Will re-crawl network metadata
+            self.assertIsNotNone(nc)
         self.assertIn('Re-crawl of metadata service', self.logs.getvalue())
         expected = {'version': 1, 'config': [
             {'mac_address': '06:17:04:d7:26:09',