diff --git a/HACKING.rst b/HACKING.rst
index 1161a350cb..f0c4ccfbd8 100644
--- a/HACKING.rst
+++ b/HACKING.rst
@@ -21,13 +21,10 @@ Nova Specific Commandments
   should be moved into a common module
 - [N313] capitalize help string
   Config parameter help strings should have a capitalized first letter
-- [N314] vim configuration should not be kept in source files.
 - [N316] Change assertTrue(isinstance(A, B)) by optimal assert like
   assertIsInstance(A, B).
 - [N317] Change assertEqual(type(A), B) by optimal assert like
   assertIsInstance(A, B)
-- [N318] Change assertEqual(A, None) or assertIs(A, None) to optimal assert
-  like assertIsNone(A)
 - [N319] Validate that debug level logs are not translated.
 - [N320] Setting CONF.* attributes directly in tests is forbidden. Use
   self.flags(option=value) instead.
@@ -64,7 +61,6 @@ Nova Specific Commandments
 - [N351] Do not use the oslo_policy.policy.Enforcer.enforce() method.
 - [N352] LOG.warn is deprecated. Enforce use of LOG.warning.
 - [N353] Validate that context objects is not passed in logging calls.
-- [N354] String interpolation should be delayed at logging calls.
 - [N355] Enforce use of assertTrue/assertFalse
 - [N356] Enforce use of assertIs/assertIsNot
 - [N357] Use oslo_utils.uuidutils or uuidsentinel(in case of test cases) to
diff --git a/nova/hacking/checks.py b/nova/hacking/checks.py
index 144ad5d2a9..b4a477adca 100644
--- a/nova/hacking/checks.py
+++ b/nova/hacking/checks.py
@@ -42,7 +42,6 @@ cfg_re = re.compile(r".*\scfg\.")
 cfg_opt_re = re.compile(r".*[\s\[]cfg\.[a-zA-Z]*Opt\(")
 rule_default_re = re.compile(r".*RuleDefault\(")
 policy_enforce_re = re.compile(r".*_ENFORCER\.enforce\(")
-vi_header_re = re.compile(r"^#\s+vim?:.+")
 virt_file_re = re.compile(r"\./nova/(?:tests/)?virt/(\w+)/")
 virt_import_re = re.compile(
     r"^\s*(?:import|from) nova\.(?:tests\.)?virt\.(\w+)")
@@ -105,9 +104,6 @@ doubled_words_re = re.compile(
     r"\b(then?|[iao]n|i[fst]|but|f?or|at|and|[dt]o)\s+\1\b")
 log_remove_context = re.compile(
     r"(.)*LOG\.(.*)\(.*(context=[_a-zA-Z0-9].*)+.*\)")
-log_string_interpolation = re.compile(r".*LOG\.(error|warning|info"
-                                      r"|critical|exception|debug)"
-                                      r"\([^,]*%[^,]*[,)]")
 return_not_followed_by_space = re.compile(r"^\s*return(?:\(|{|\"|'|#).*$")
 
 
@@ -248,20 +244,6 @@ def capital_cfg_help(logical_line, tokens):
                     yield(0, msg)
 
 
-def no_vi_headers(physical_line, line_number, lines):
-    """Check for vi editor configuration in source files.
-
-    By default vi modelines can only appear in the first or
-    last 5 lines of a source file.
-
-    N314
-    """
-    # NOTE(gilliard): line_number is 1-indexed
-    if line_number <= 5 or line_number > len(lines) - 5:
-        if vi_header_re.match(physical_line):
-            return 0, "N314: Don't put vi configuration in source files"
-
-
 def assert_true_instance(logical_line):
     """Check for assertTrue(isinstance(a, b)) sentences
 
@@ -280,27 +262,6 @@ def assert_equal_type(logical_line):
         yield (0, "N317: assertEqual(type(A), B) sentences not allowed")
 
 
-def assert_equal_none(logical_line):
-    """Check for assertEqual(A, None) or assertEqual(None, A) sentences
-
-    N318
-    """
-    _start_re = re.compile(r"assertEqual\(.*?,\s+None\)$")
-    _end_re = re.compile(r"assertEqual\(None,")
-
-    if _start_re.search(logical_line) or _end_re.search(logical_line):
-        yield (0, "N318: assertEqual(A, None) or assertEqual(None, A) "
-               "sentences not allowed. Use assertIsNone(A) instead.")
-
-    _start_re = re.compile(r"assertIs(Not)?\(None,")
-    _end_re = re.compile(r"assertIs(Not)?\(.*,\s+None\)$")
-
-    if _start_re.search(logical_line) or _end_re.search(logical_line):
-        yield (0, "N318: assertIsNot(A, None) or assertIsNot(None, A) must "
-               "not be used. Use assertIsNone(A) or assertIsNotNone(A) "
-               "instead.")
-
-
 def check_python3_xrange(logical_line):
     if re.search(r"\bxrange\s*\(", logical_line):
         yield(0, "N327: Do not use xrange(). 'xrange()' is not compatible "
@@ -803,28 +764,6 @@ def check_context_log(logical_line, physical_line, filename):
               "kwarg.")
 
 
-def check_delayed_string_interpolation(logical_line, physical_line, filename):
-    """Check whether string interpolation is delayed at logging calls
-
-    Not correct: LOG.debug('Example: %s' % 'bad')
-    Correct:     LOG.debug('Example: %s', 'good')
-
-    N354
-    """
-    if "nova/tests" in filename:
-        return
-
-    if pep8.noqa(physical_line):
-        return
-
-    if log_string_interpolation.match(logical_line):
-        yield(logical_line.index('%'),
-              "N354: String interpolation should be delayed to be "
-              "handled by the logging code, rather than being done "
-              "at the point of the logging call. "
-              "Use ',' instead of '%'.")
-
-
 def no_assert_equal_true_false(logical_line):
     """Enforce use of assertTrue/assertFalse.
 
@@ -901,11 +840,9 @@ def factory(register):
     register(import_no_virt_driver_import_deps)
     register(import_no_virt_driver_config_deps)
     register(capital_cfg_help)
-    register(no_vi_headers)
     register(no_import_translation_in_tests)
     register(assert_true_instance)
     register(assert_equal_type)
-    register(assert_equal_none)
     register(assert_raises_regexp)
     register(no_translate_debug_logs)
     register(no_setting_conf_directly_in_tests)
@@ -934,7 +871,6 @@ def factory(register):
     register(no_log_warn)
     register(CheckForUncalledTestClosure)
     register(check_context_log)
-    register(check_delayed_string_interpolation)
     register(no_assert_equal_true_false)
     register(no_assert_true_false_is_not)
     register(check_uuid4)
diff --git a/nova/tests/functional/integrated_helpers.py b/nova/tests/functional/integrated_helpers.py
index 192b465592..bd123d8945 100644
--- a/nova/tests/functional/integrated_helpers.py
+++ b/nova/tests/functional/integrated_helpers.py
@@ -57,7 +57,7 @@ def generate_new_element(items, prefix, numeric=False):
             candidate = prefix + generate_random_alphanumeric(8)
         if candidate not in items:
             return candidate
-        LOG.debug("Random collision on %s" % candidate)
+        LOG.debug("Random collision on %s", candidate)
 
 
 class _IntegratedTestBase(test.TestCase):
@@ -143,7 +143,7 @@ class _IntegratedTestBase(test.TestCase):
 
         # Set a valid flavorId
         flavor = self.api.get_flavors()[0]
-        LOG.debug("Using flavor: %s" % flavor)
+        LOG.debug("Using flavor: %s", flavor)
         server[self._flavor_ref_parameter] = ('http://fake.server/%s'
                                               % flavor['id'])
 
@@ -184,14 +184,14 @@ class _IntegratedTestBase(test.TestCase):
     def _build_server(self, flavor_id):
         server = {}
         image = self.api.get_images()[0]
-        LOG.debug("Image: %s" % image)
+        LOG.debug("Image: %s", image)
 
         # We now have a valid imageId
         server[self._image_ref_parameter] = image['id']
 
         # Set a valid flavorId
         flavor = self.api.get_flavor(flavor_id)
-        LOG.debug("Using flavor: %s" % flavor)
+        LOG.debug("Using flavor: %s", flavor)
         server[self._flavor_ref_parameter] = ('http://fake.server/%s'
                                               % flavor['id'])
 
diff --git a/nova/tests/functional/libvirt/test_numa_servers.py b/nova/tests/functional/libvirt/test_numa_servers.py
index 54b41c6c60..e94a279a29 100644
--- a/nova/tests/functional/libvirt/test_numa_servers.py
+++ b/nova/tests/functional/libvirt/test_numa_servers.py
@@ -78,7 +78,7 @@ class NUMAServersTest(ServersTestBase):
         post = {'server': good_server}
 
         created_server = self.api.post_server(post)
-        LOG.debug("created_server: %s" % created_server)
+        LOG.debug("created_server: %s", created_server)
         self.assertTrue(created_server['id'])
         created_server_id = created_server['id']
 
diff --git a/nova/tests/functional/libvirt/test_pci_sriov_servers.py b/nova/tests/functional/libvirt/test_pci_sriov_servers.py
index 4f62f7d82c..6bf8c2377e 100644
--- a/nova/tests/functional/libvirt/test_pci_sriov_servers.py
+++ b/nova/tests/functional/libvirt/test_pci_sriov_servers.py
@@ -105,7 +105,7 @@ class SRIOVServersTest(ServersTestBase):
         post = {'server': good_server}
 
         created_server = self.api.post_server(post)
-        LOG.debug("created_server: %s" % created_server)
+        LOG.debug("created_server: %s", created_server)
         self.assertTrue(created_server['id'])
         created_server_id = created_server['id']
 
diff --git a/nova/tests/functional/test_servers.py b/nova/tests/functional/test_servers.py
index 0f3df6b12f..107dcf562a 100644
--- a/nova/tests/functional/test_servers.py
+++ b/nova/tests/functional/test_servers.py
@@ -78,7 +78,7 @@ class ServersTestBase(integrated_helpers._IntegratedTestBase):
                 LOG.debug("Got 404, proceeding")
                 break
 
-            LOG.debug("Found_server=%s" % found_server)
+            LOG.debug("Found_server=%s", found_server)
 
             # TODO(justinsb): Mock doesn't yet do accurate state changes
             # if found_server['status'] != 'deleting':
@@ -109,7 +109,7 @@ class ServersTest(ServersTestBase):
         # Simple check that listing servers works.
         servers = self.api.get_servers()
         for server in servers:
-            LOG.debug("server: %s" % server)
+            LOG.debug("server: %s", server)
 
     def test_create_server_with_error(self):
         # Create a server which will enter error state.
@@ -174,7 +174,7 @@ class ServersTest(ServersTestBase):
         server['name'] = good_server['name']
 
         created_server = self.api.post_server(post)
-        LOG.debug("created_server: %s" % created_server)
+        LOG.debug("created_server: %s", created_server)
         self.assertTrue(created_server['id'])
         created_server_id = created_server['id']
 
@@ -215,7 +215,7 @@ class ServersTest(ServersTestBase):
         server = self._build_minimal_create_server_request()
 
         created_server = self.api.post_server({'server': server})
-        LOG.debug("created_server: %s" % created_server)
+        LOG.debug("created_server: %s", created_server)
         self.assertTrue(created_server['id'])
         created_server_id = created_server['id']
 
@@ -250,7 +250,7 @@ class ServersTest(ServersTestBase):
         server = self._build_minimal_create_server_request()
 
         created_server = self.api.post_server({'server': server})
-        LOG.debug("created_server: %s" % created_server)
+        LOG.debug("created_server: %s", created_server)
         self.assertTrue(created_server['id'])
         created_server_id = created_server['id']
 
@@ -282,7 +282,7 @@ class ServersTest(ServersTestBase):
         server = self._build_minimal_create_server_request()
 
         created_server = self.api.post_server({'server': server})
-        LOG.debug("created_server: %s" % created_server)
+        LOG.debug("created_server: %s", created_server)
         self.assertTrue(created_server['id'])
         created_server_id = created_server['id']
 
@@ -320,7 +320,7 @@ class ServersTest(ServersTestBase):
 
         post = {'server': server}
         created_server = self.api.post_server(post)
-        LOG.debug("created_server: %s" % created_server)
+        LOG.debug("created_server: %s", created_server)
         self.assertTrue(created_server['id'])
         created_server_id = created_server['id']
 
@@ -402,7 +402,7 @@ class ServersTest(ServersTestBase):
         server_post['server']['metadata'] = metadata
 
         created_server = self.api.post_server(server_post)
-        LOG.debug("created_server: %s" % created_server)
+        LOG.debug("created_server: %s", created_server)
         self.assertTrue(created_server['id'])
         created_server_id = created_server['id']
 
@@ -420,7 +420,7 @@ class ServersTest(ServersTestBase):
         post['rebuild'].update(self._get_access_ips_params())
 
         self.api.post_server_action(created_server_id, post)
-        LOG.debug("rebuilt server: %s" % created_server)
+        LOG.debug("rebuilt server: %s", created_server)
         self.assertTrue(created_server['id'])
 
         found_server = self.api.get_server(created_server_id)
@@ -439,7 +439,7 @@ class ServersTest(ServersTestBase):
         }
 
         self.api.post_server_action(created_server_id, post)
-        LOG.debug("rebuilt server: %s" % created_server)
+        LOG.debug("rebuilt server: %s", created_server)
         self.assertTrue(created_server['id'])
 
         found_server = self.api.get_server(created_server_id)
@@ -459,7 +459,7 @@ class ServersTest(ServersTestBase):
         # Create a server
         server = self._build_minimal_create_server_request()
         created_server = self.api.post_server({'server': server})
-        LOG.debug("created_server: %s" % created_server)
+        LOG.debug("created_server: %s", created_server)
         server_id = created_server['id']
         self.assertTrue(server_id)
 
@@ -534,7 +534,7 @@ class ServersTest(ServersTestBase):
         post = {'server': server}
 
         created_server = self.api.post_server(post)
-        LOG.debug("created_server: %s" % created_server)
+        LOG.debug("created_server: %s", created_server)
         self.assertTrue(created_server['id'])
         created_server_id = created_server['id']
 
diff --git a/nova/tests/functional/wsgi/test_secgroup.py b/nova/tests/functional/wsgi/test_secgroup.py
index 33ca2f6521..a2d0b4a8cd 100644
--- a/nova/tests/functional/wsgi/test_secgroup.py
+++ b/nova/tests/functional/wsgi/test_secgroup.py
@@ -62,7 +62,7 @@ class SecgroupsFullstack(testscenarios.WithScenarios, test.TestCase):
         server = {}
 
         image = self.api.get_images()[0]
-        LOG.info("Image: %s" % image)
+        LOG.info("Image: %s", image)
 
         if self._image_ref_parameter in image:
             image_href = image[self._image_ref_parameter]
diff --git a/nova/tests/unit/network/test_manager.py b/nova/tests/unit/network/test_manager.py
index 2d8a800f2f..32d1dd7295 100644
--- a/nova/tests/unit/network/test_manager.py
+++ b/nova/tests/unit/network/test_manager.py
@@ -3510,7 +3510,7 @@ class LdapDNSTestCase(test.NoDBTestCase):
 
         self.driver.delete_entry(name1, domain1)
         entries = self.driver.get_entries_by_address(address1, domain1)
-        LOG.debug("entries: %s" % entries)
+        LOG.debug("entries: %s", entries)
         self.assertEqual(1, len(entries))
         self.assertEqual(name2, entries[0])
 
diff --git a/nova/tests/unit/test_hacking.py b/nova/tests/unit/test_hacking.py
index f1b603dddf..aa138404fc 100644
--- a/nova/tests/unit/test_hacking.py
+++ b/nova/tests/unit/test_hacking.py
@@ -82,30 +82,6 @@ class HackingTestCase(test.NoDBTestCase):
             "'nova.virt.libvirt.driver', group='libvirt')",
             "./nova/virt/libvirt/volume.py"))
 
-    def test_no_vi_headers(self):
-
-        lines = ['Line 1\n', 'Line 2\n', 'Line 3\n', 'Line 4\n', 'Line 5\n',
-                 'Line 6\n', 'Line 7\n', 'Line 8\n', 'Line 9\n', 'Line 10\n',
-                 'Line 11\n', 'Line 12\n', 'Line 13\n', 'Line14\n', 'Line15\n']
-
-        self.assertIsNone(checks.no_vi_headers(
-            "Test string foo", 1, lines))
-        self.assertEqual(len(list(checks.no_vi_headers(
-            "# vim: et tabstop=4 shiftwidth=4 softtabstop=4",
-            2, lines))), 2)
-        self.assertIsNone(checks.no_vi_headers(
-            "# vim: et tabstop=4 shiftwidth=4 softtabstop=4",
-            6, lines))
-        self.assertIsNone(checks.no_vi_headers(
-            "# vim: et tabstop=4 shiftwidth=4 softtabstop=4",
-            9, lines))
-        self.assertEqual(len(list(checks.no_vi_headers(
-            "# vim: et tabstop=4 shiftwidth=4 softtabstop=4",
-            14, lines))), 2)
-        self.assertIsNone(checks.no_vi_headers(
-            "Test end string for vi",
-            15, lines))
-
     def test_assert_true_instance(self):
         self.assertEqual(len(list(checks.assert_true_instance(
             "self.assertTrue(isinstance(e, "
@@ -158,28 +134,6 @@ class HackingTestCase(test.NoDBTestCase):
         self.assertEqual(len(list(checks.assert_equal_in(
             "self.assertEqual(False, any(a==1 for a in b))"))), 0)
 
-    def test_assert_equal_none(self):
-        self.assertEqual(len(list(checks.assert_equal_none(
-            "self.assertEqual(A, None)"))), 1)
-
-        self.assertEqual(len(list(checks.assert_equal_none(
-            "self.assertEqual(None, A)"))), 1)
-
-        self.assertEqual(
-            len(list(checks.assert_equal_none("self.assertIsNone()"))), 0)
-
-        self.assertEqual(len(list(checks.assert_equal_none(
-            "self.assertIs(A, None)"))), 1)
-
-        self.assertEqual(len(list(checks.assert_equal_none(
-            "self.assertIsNot(A, None)"))), 1)
-
-        self.assertEqual(len(list(checks.assert_equal_none(
-            "self.assertIs(None, A)"))), 1)
-
-        self.assertEqual(len(list(checks.assert_equal_none(
-            "self.assertIsNot(None, A)"))), 1)
-
     def test_assert_true_or_false_with_in_or_not_in(self):
         self.assertEqual(len(list(checks.assert_true_or_false_with_in(
             "self.assertTrue(A in B)"))), 1)
@@ -793,57 +747,6 @@ class HackingTestCase(test.NoDBTestCase):
                """
         self._assert_has_no_errors(code, checks.check_context_log)
 
-    def test_check_delayed_string_interpolation(self):
-        checker = checks.check_delayed_string_interpolation
-        code = """
-               msg_w = _LW('Test string (%s)')
-               msg_i = _LI('Test string (%s)')
-               value = 'test'
-
-               LOG.error(_LE("Test string (%s)") % value)
-               LOG.warning(msg_w % 'test%string')
-               LOG.info(msg_i %
-                        "test%string%info")
-               LOG.critical(
-                   _LC('Test string (%s)') % value,
-                   instance=instance)
-               LOG.exception(_LE(" 'Test quotation %s' \"Test\"") % 'test')
-               LOG.debug(' "Test quotation %s" \'Test\'' % "test")
-               LOG.debug('Tesing %(test)s' %
-                         {'test': ','.join(
-                             ['%s=%s' % (name, value)
-                              for name, value in test.items()])})
-               """
-
-        expected_errors = [(5, 34, 'N354'), (6, 18, 'N354'), (7, 15, 'N354'),
-                           (10, 28, 'N354'), (12, 49, 'N354'),
-                           (13, 40, 'N354'), (14, 28, 'N354')]
-        self._assert_has_errors(code, checker, expected_errors=expected_errors)
-        self._assert_has_no_errors(code, checker,
-                                   filename='nova/tests/unit/test_hacking.py')
-
-        code = """
-               msg_w = _LW('Test string (%s)')
-               msg_i = _LI('Test string (%s)')
-               value = 'test'
-
-               LOG.error(_LE("Test string (%s)"), value)
-               LOG.error(_LE("Test string (%s)") % value) # noqa
-               LOG.warning(msg_w, 'test%string')
-               LOG.info(msg_i,
-                        "test%string%info")
-               LOG.critical(
-                   _LC('Test string (%s)'), value,
-                   instance=instance)
-               LOG.exception(_LE(" 'Test quotation %s' \"Test\""), 'test')
-               LOG.debug(' "Test quotation %s" \'Test\'', "test")
-               LOG.debug('Tesing %(test)s',
-                         {'test': ','.join(
-                             ['%s=%s' % (name, value)
-                              for name, value in test.items()])})
-               """
-        self._assert_has_no_errors(code, checker)
-
     def test_no_assert_equal_true_false(self):
         code = """
                   self.assertEqual(context_is_admin, True)
diff --git a/nova/tests/unit/virt/libvirt/test_fakelibvirt.py b/nova/tests/unit/virt/libvirt/test_fakelibvirt.py
index 4918ce0d05..8579df9592 100644
--- a/nova/tests/unit/virt/libvirt/test_fakelibvirt.py
+++ b/nova/tests/unit/virt/libvirt/test_fakelibvirt.py
@@ -82,7 +82,7 @@ class FakeLibvirtTests(test.NoDBTestCase):
     def test_openAuth_accepts_None_uri_by_default(self):
         conn_method = self.get_openAuth_curry_func()
         conn = conn_method(None)
-        self.assertNotEqual(conn, None, "Connecting to fake libvirt failed")
+        self.assertIsNotNone(conn, "Connecting to fake libvirt failed")
 
     def test_openAuth_can_refuse_None_uri(self):
         conn_method = self.get_openAuth_curry_func()
diff --git a/nova/tests/unit/virt/test_virt_drivers.py b/nova/tests/unit/virt/test_virt_drivers.py
index 302008a22d..faae06e22a 100644
--- a/nova/tests/unit/virt/test_virt_drivers.py
+++ b/nova/tests/unit/virt/test_virt_drivers.py
@@ -60,7 +60,7 @@ def catch_notimplementederror(f):
         except NotImplementedError:
             frame = traceback.extract_tb(sys.exc_info()[2])[-1]
             LOG.error("%(driver)s does not implement %(method)s "
-                      "required for test %(test)s" %
+                      "required for test %(test)s",
                       {'driver': type(self.connection),
                        'method': frame[2], 'test': f.__name__})
 
diff --git a/tox.ini b/tox.ini
index e19dd4048d..31b5e302c2 100644
--- a/tox.ini
+++ b/tox.ini
@@ -161,6 +161,7 @@ commands = bash -c tools/releasenotes_tox.sh
 #
 # E251 Skipped due to https://github.com/jcrocholl/pep8/issues/301
 
+enable-extensions = H106,H203,H904
 ignore = E121,E122,E123,E124,E125,E126,E127,E128,E129,E131,E251,H405
 exclude =  .venv,.git,.tox,dist,doc,*lib/python*,*egg,build,tools/xenserver*,releasenotes
 # To get a list of functions that are more complex than 25, set max-complexity