tox: bump the pinned flake8 and pylint version (#1029)

tox: bump the pinned flake8 and pylint version

* pylint: fix W1406 (redundant-u-string-prefix)

The u prefix for strings is no longer necessary in Python >=3.0.

* pylint: disable W1514 (unspecified-encoding)
    
From https://www.python.org/dev/peps/pep-0597/ (Python 3.10):
    
The new warning stems form https://www.python.org/dev/peps/pep-0597,
which says:
    
  Developers using macOS or Linux may forget that the default encoding
  is not always UTF-8. [...] Even Python experts may assume that the
  default encoding is UTF-8. This creates bugs that only happen on Windows.
    
The warning could be fixed by always specifying encoding='utf-8',
however we should be careful to not break environments which are not
utf-8 (or explicitly state that only utf-8 is supported). Let's silence
the warning for now.

* _quick_read_instance_id: cover the case where load_yaml() returns None

Spotted by pylint:
 - E1135 (unsupported-membership-test)
 - E1136 (unsubscriptable-object)

LP: #1944414

5 files changed, 13 insertions, 13 deletions

diff --git a/cloudinit/reporting/handlers.py b/cloudinit/reporting/handlers.py
index 0a8c7af3..e32739ef 100755
--- a/cloudinit/reporting/handlers.py
+++ b/cloudinit/reporting/handlers.py
@@ -137,8 +137,8 @@ class HyperVKvpReportingHandler(ReportingHandler):
         self._event_types = event_types
         self.q = queue.Queue()
         self.incarnation_no = self._get_incarnation_no()
-        self.event_key_prefix = u"{0}|{1}".format(self.EVENT_PREFIX,
-                                                  self.incarnation_no)
+        self.event_key_prefix = "{0}|{1}".format(self.EVENT_PREFIX,
+                                                 self.incarnation_no)
         self.publish_thread = threading.Thread(
             target=self._publish_event_routine
         )
@@ -200,9 +200,9 @@ class HyperVKvpReportingHandler(ReportingHandler):
         CLOUD_INIT|<incarnation number>|<event_type>|<event_name>|<uuid>
         [|subevent_index]
         """
-        return u"{0}|{1}|{2}|{3}".format(self.event_key_prefix,
-                                         event.event_type, event.name,
-                                         uuid.uuid4())
+        return "{0}|{1}|{2}|{3}".format(self.event_key_prefix,
+                                        event.event_type, event.name,
+                                        uuid.uuid4())
 
     def _encode_kvp_item(self, key, value):
         data = struct.pack(
diff --git a/cloudinit/safeyaml.py b/cloudinit/safeyaml.py
index d6f5f95b..b95df27d 100644
--- a/cloudinit/safeyaml.py
+++ b/cloudinit/safeyaml.py
@@ -15,7 +15,7 @@ class _CustomSafeLoader(yaml.SafeLoader):
 
 
 _CustomSafeLoader.add_constructor(
-    u'tag:yaml.org,2002:python/unicode',
+    'tag:yaml.org,2002:python/unicode',
     _CustomSafeLoader.construct_python_unicode)
 
 
diff --git a/cloudinit/sources/DataSourceNoCloud.py b/cloudinit/sources/DataSourceNoCloud.py
index a126aad3..2d9e86b4 100644
--- a/cloudinit/sources/DataSourceNoCloud.py
+++ b/cloudinit/sources/DataSourceNoCloud.py
@@ -247,7 +247,7 @@ def _quick_read_instance_id(dirs=None):
         try:
             data = util.pathprefix2dict(d, required=['meta-data'])
             md = util.load_yaml(data['meta-data'])
-            if iid_key in md:
+            if md and iid_key in md:
                 return md[iid_key]
         except ValueError:
             pass
diff --git a/cloudinit/templater.py b/cloudinit/templater.py
index a00ade20..009bed32 100644
--- a/cloudinit/templater.py
+++ b/cloudinit/templater.py
@@ -36,14 +36,14 @@ from cloudinit import util
 LOG = logging.getLogger(__name__)
 TYPE_MATCHER = re.compile(r"##\s*template:(.*)", re.I)
 BASIC_MATCHER = re.compile(r'\$\{([A-Za-z0-9_.]+)\}|\$([A-Za-z0-9_.]+)')
-MISSING_JINJA_PREFIX = u'CI_MISSING_JINJA_VAR/'
+MISSING_JINJA_PREFIX = 'CI_MISSING_JINJA_VAR/'
 
 
 class UndefinedJinjaVariable(JUndefined):
     """Class used to represent any undefined jinja template variable."""
 
     def __str__(self):
-        return u'%s%s' % (MISSING_JINJA_PREFIX, self._undefined_name)
+        return '%s%s' % (MISSING_JINJA_PREFIX, self._undefined_name)
 
     def __sub__(self, other):
         other = str(other).replace(MISSING_JINJA_PREFIX, '')
diff --git a/cloudinit/tests/test_subp.py b/cloudinit/tests/test_subp.py
index 911c1f3d..515d5d64 100644
--- a/cloudinit/tests/test_subp.py
+++ b/cloudinit/tests/test_subp.py
@@ -91,8 +91,8 @@ class TestSubp(CiTestCase):
         tmp_file = self.tmp_path('test.out')
         cmd = 'echo HI MOM >> {tmp_file}'.format(tmp_file=tmp_file)
         (out, _err) = subp.subp(cmd.encode('utf-8'), shell=True)
-        self.assertEqual(u'', out)
-        self.assertEqual(u'', _err)
+        self.assertEqual('', out)
+        self.assertEqual('', _err)
         self.assertEqual('HI MOM\n', util.load_file(tmp_file))
 
     def test_subp_handles_strings(self):
@@ -100,8 +100,8 @@ class TestSubp(CiTestCase):
         tmp_file = self.tmp_path('test.out')
         cmd = 'echo HI MOM >> {tmp_file}'.format(tmp_file=tmp_file)
         (out, _err) = subp.subp(cmd, shell=True)
-        self.assertEqual(u'', out)
-        self.assertEqual(u'', _err)
+        self.assertEqual('', out)
+        self.assertEqual('', _err)
         self.assertEqual('HI MOM\n', util.load_file(tmp_file))
 
     def test_subp_handles_utf8(self):