Run pyupgrade to clean up Python 2 syntaxes

Update all .py source files by
 $ pyupgrade --py3-only $(git ls-files | grep ".py$")
to modernize the code according to Python 3 syntaxes.

Change-Id: Ic6336f745f65161bb05defca797480bc03f7fea7

os_refresh_config/os_refresh_config.py

@@ -114,8 +114,8 @@ def main(argv=sys.argv):
     lock = open(options.lockfile, 'a')
     try:
         fcntl.flock(lock, fcntl.LOCK_EX | fcntl.LOCK_NB)
-    except IOError as e:
-        log.error('Could not lock %s. %s' % (options.lockfile, e))
+    except OSError as e:
+        log.error('Could not lock {}. {}'.format(options.lockfile, e))
         return e.errno
 
     lock.truncate(0)
@@ -144,7 +144,7 @@ def main(argv=sys.argv):
                 sys.stderr.flush()
                 log.info('Completed phase %s' % phase)
             except subprocess.CalledProcessError as e:
-                log.error("during %s phase. [%s]\n" % (phase, e))
+                log.error("during {} phase. [{}]\n".format(phase, e))
                 error_dir = os.path.join(BASE_DIR, 'error.d')
                 if os.path.exists(error_dir):
                     log.info('Calling error handlers.')

os_refresh_config/tests/functional/test_cmd.py

@@ -21,7 +21,7 @@ import testtools
 class TestCmd(testtools.TestCase):
 
     def setUp(self):
-        super(TestCmd, self).setUp()
+        super().setUp()
         self.useFixture(fixtures.NestedTempfile())
         self.base_dir = self.useFixture(fixtures.TempDir())
         self.lockdir = self.useFixture(fixtures.TempDir())

os_refresh_config/tests/unit/test_main.py

@@ -22,7 +22,7 @@ from os_refresh_config import os_refresh_config
 
 class TestMain(testtools.TestCase):
     def setUp(self):
-        super(TestMain, self).setUp()
+        super().setUp()
         self.useFixture(fixtures.NestedTempfile())
         td = self.useFixture(fixtures.TempDir())
         self.useFixture(