Bump flake8 to 5.0 to pick up fixes

There is a bug [1] in older flake8 that we need to pick up. In
particular, Nova has at least one line longer than 80 characters in it
[2] because of that bug. Our own unit tests start breaking with the
new flake8, so we need to fix whitespace for one `if`, and start
calling flake8 with `--enable-extentions` to force flake8 to load
extensions decorated with @off_by_default.

[1] https://github.com/PyCQA/flake8/issues/1534
[2] 5c32d5efe1/nova/image/glance.py (L392)

Change-Id: I7799049924b5a2cde867c88c03154c36831c9670

hacking/checks/python23.py

@@ -158,8 +158,11 @@ def hacking_python3x_metaclass(logical_line, noqa):
     if noqa:
         return
     split_line = logical_line.split()
-    if(len(split_line) > 2 and split_line[0] == '__metaclass__' and
-       split_line[1] == '='):
+    if (
+        len(split_line) > 2
+        and split_line[0] == '__metaclass__'
+        and split_line[1] == '='
+    ):
         yield (logical_line.find('__metaclass__'),
                "H236: Python 3.x incompatible __metaclass__, "
                "use six.add_metaclass()")

hacking/tests/test_doctest.py

@@ -40,7 +40,8 @@ class HackingTestCase(hacking.tests.TestCase):
             f.write(''.join(self.lines))
 
         cmd = [sys.executable, '-mflake8', '--isolated',
-               '--select=%s' % self.code, '--ignore=F',
+               '--select=%s' % self.code,
+               '--enable-extensions=%s' % self.code, '--ignore=F',
                '--format=%(code)s\t%(path)s\t%(row)d', f.name]
         out, _ = subprocess.Popen(cmd, stdout=subprocess.PIPE).communicate()
 
@@ -52,6 +53,7 @@ class HackingTestCase(hacking.tests.TestCase):
             self.addDetail('reason',
                            content.text_content("Failed to trigger rule %s" %
                                                 self.code))
+
             self.assertNotEqual('', out)
             self.assertEqual(self.code, out.split('\t')[0].rstrip(':'), out)
 

requirements.txt

@@ -1 +1 @@
-flake8~=4.0.1 # MIT
+flake8~=5.0.1 # MIT