Fix lint in unit tests re: py3-first and py2 compat

Change-Id: Icdcbeaffac1b001dcffbbf9376ef2b90c373f170

tox.ini

@@ -32,7 +32,6 @@ deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 
 [testenv:pep8]
-basepython = python2.7
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 commands = flake8 {posargs} hooks unit_tests tests actions lib

unit_tests/testing.py

@@ -40,7 +40,7 @@ def load_config():
 
     if not config:
         logging.error('Could not find config.yaml in any parent directory '
-                      'of %s. ' % file)
+                      'of %s. ' % __file__)
         raise Exception
 
     return yaml.safe_load(open(config).read())['options']
@@ -127,7 +127,7 @@ def patch_open():
 
     Yields the mock for "open" and "file", respectively.'''
     mock_open = MagicMock(spec=open)
-    mock_file = MagicMock(spec=file)
+    mock_file = MagicMock(spec=file)  # noqa - transitional py2 py3 lint work-around
 
     @contextmanager
     def stub_open(*args, **kwargs):